@article{PrommesbergerLangerŁawrowskietal., author = {Prommesberger, Christian and Langer, Christoph and Ławrowski, Robert Damian and Schreiner, Rupert}, title = {Investigations on the long-term performance of gated p-type silicon tip arrays with reproducible and stable field emission behavior}, series = {Journal of Vacuum Science \& Technology B}, volume = {35}, journal = {Journal of Vacuum Science \& Technology B}, number = {1}, doi = {10.1116/1.4972519}, abstract = {The authors report on the fabrication and characterization of p-type Si tip arrays with an integrated gate electrode for applications as field emission electron sources. After the reactive ion etching of the emitters, the combined thermal dry and wet oxidation was used for both the sharpening of the emitters and for the realization of an enhanced insulation layer. Au was evaporated in a self-aligned process as gate electrode. Arrays of 16 Si tips were fabricated with tip heights of about 3 μm and tip radii of about 20 nm with integrated gate electrode concentrically positioned ≈2 μm below the tip apex. Integral measurements with an additional anode showed improved field emission properties with a reproducible and stable emission behavior. A fast activation of the tips, low onset voltages of about 30 V, and moderate field emission currents up to 0.55 μA were noticed. The field emission parameters were calculated using the Fowler-Nordheim characteristics. A pronounced saturation regime was observed, and current fluctuations of less than ±1\% were investigated for 30 min. Long-term measurements were carried out for a period of more than 8 h. In the first 6 h of operation, the authors observed a drift of the emission current from 0.35 to 0.55 μA caused by an increased emission surface.}, language = {en} } @inproceedings{BiekerRoustaieLangeretal., author = {Bieker, Johannes and Roustaie, Farough and Langer, Christoph and Schreiner, Rupert and Schlaak, Helmut F.}, title = {Innovatives Verfahren zur Herstellung und Integration metallischer Nanokonen f{\"u}r die Feldemission}, series = {MikroSystemTechnik Kongress 2017 : MEMS, Mikroelektronik, Systeme 23.-25. Oktober 2017 in M{\"u}nchen}, booktitle = {MikroSystemTechnik Kongress 2017 : MEMS, Mikroelektronik, Systeme 23.-25. Oktober 2017 in M{\"u}nchen}, number = {CD-ROM}, publisher = {VDE-Verlag}, address = {M{\"u}nchen}, isbn = {978-3-8007-4491-6}, pages = {797 -- 800}, abstract = {In den letzten Jahren wurde am Institut f{\"u}r Elektromechanische Konstruktionen die Fabrikation und Integration von metallischen Nanodr{\"a}hten und Nanokonen mittels Template-basierter Abscheidung erforscht. Diese Variante der in-situ Abscheidung von metallischen Nanostrukturen bietet eine Vielzahl von Anwendungsm{\"o}glichkeiten. Im Rahmen dieses Beitrags werden das Herstellungsverfahren zur Herstellung metallischer Nanokonen vorgestellt. Dies beinhaltet sowohl die Templatepr{\"a}paration mittels asymmetrischen {\"A}tzens als auch die anschließende Integration mittels galvanischer Abscheidung. Eine Anwendung der metallischen Nanokonen stellt die Verwendung als Feldemitter in der Vakuumelektronik dar. Es werden erste Messungen der Langzeitstabilit{\"a}t des Feldemissionsstromes der metallischen Konen pr{\"a}sentiert.}, language = {de} } @inproceedings{ŁawrowskiLangerPrommesbergeretal., author = {Ławrowski, Robert Damian and Langer, Christoph and Prommesberger, Christian and Dams, Florian and Bachmann, Michael and Schreiner, Rupert}, title = {Fabrication and simulation of silicon structures with high aspect ratio for field emission devices}, series = {2014 27th International Vacuum Nanoelectronics Conference (IVNC), 6-10 July 2014, Engelberg, Switzerland}, booktitle = {2014 27th International Vacuum Nanoelectronics Conference (IVNC), 6-10 July 2014, Engelberg, Switzerland}, publisher = {IEEE}, doi = {10.1109/IVNC.2014.6894805}, pages = {193 -- 194}, abstract = {To obtain higher field enhancement factors of Si-tip structures, we present an improved fabrication process utilizing reactive-ion etching (RIE) with an inductively coupled plasma (ICP). In our design, a pillar under the tips is realized by a combination of RIE with ICP. With adjusted power settings (≈ 240 W) and step times (<; 5 s), vertical slopes with a low roughness of approximately 10 nm to 20 nm are possible. The remaining silicon is oxidized thermally to sharpen the emitters. A final tip radius of R <; 20 nm is obtained for the tips of the emitters. The pillar height HP can be mainly adjusted by the duration of the ICP-etching step. A total emitter height of H ≈ 6 μm with a pillar height of HP ≈ 5 μm is achieved. Simulations with COMSOL Multiphysics® are applied to calculate the field enhancement factor β. A two-dimensional model is used in rotational symmetry. In addition to the previous model, a pillar with a varying diameter {\O}P and height HP is added. A conventional emitter (H = 1 μm and R = 20 nm) placed on a pillar of the height HP ≈ 5 μm approximately results in a three times higher β-factor (β≈ 105). By decreasing the diameter {\O}P a slight increase of the β-factor is observed. However, the aspect ratio of the emitter mainly influences on the β-factor.}, language = {en} } @article{BachmannDuesbergLangeretal., author = {Bachmann, Michael and D{\"u}sberg, Felix and Langer, Christoph and Herdl, Florian and Bergbreiter, Lukas and Dams, Florian and Miyakawa, Natuski and Eggert, Tobias and Pahlke, Andreas and Edler, Simon and Prommesberger, Christian and Ławrowski, Robert Damian and Hausladen, Matthias and Schreiner, Rupert}, title = {Vacuum-sealed field emission electron gun}, series = {Journal of Vacuum Science \& Technology B}, volume = {38}, journal = {Journal of Vacuum Science \& Technology B}, number = {2}, publisher = {AIP Publishing}, doi = {10.1116/1.5139316}, abstract = {A compact vacuum-sealed field emission electron gun with an operation voltage below 5 kV is presented. With a 150 nm thick pyrolytic carbon membrane, a transmission of 40\% at 5 kV is obtained. For more than 2500 h of continuous operation at an emission current of 100 nA, no significant increase (<50V ) and almost no degradation were found. From this measurement, a lifetime of more than 10 000 h at continuous operation with approximately a linear increase of the extraction voltage from about 545 V to about 730 V is predicted. This electron source enables application of field emitter arrays in poor vacuum or even ambient pressure. ACKNOWLEDGMENT This work was supported by the German Federal Ministry for Economic Affairs and Energy under Project No. ZF4081502GM8. C.P., R.L., M.H., and R.S. were supported by Grant No. ZF4562901GM8.}, language = {en} } @article{EdlerBachmannBreueretal., author = {Edler, Simon and Bachmann, Michael and Breuer, Janis and Dams, Florian and D{\"u}sberg, Felix and Hofmann, Martin and Jakšič, Jasna and Pahlke, Andreas and Langer, Christoph and Ławrowski, Robert Damian and Prommesberger, Christian and Schreiner, Rupert}, title = {Influence of adsorbates on the performance of a field emitter array in a high voltage triode setup}, series = {Journal of Applied Physics}, volume = {122}, journal = {Journal of Applied Physics}, doi = {10.1063/1.4987134}, abstract = {In the present work, black-silicon field emitter arrays (FEAs) are investigated regarding the influence of residual gas pressure on the characteristics and lifetime in the high voltage triode setup. Current-voltage-characteristics at different pressure levels are recorded and show a decreasing emission current with rising pressure. This decrease can be explained by an increase of the work function and charging of the emitter surface caused by adsorbates. The emission current can be restored to its initial value by heating of the FEA up to 110 °C during active emission. With this regeneration procedure, an extended lifetime from about 20 h to 440 h at a residual gas pressure of 10-5 mbar is achieved.}, language = {en} } @article{KleshchSerbunLuetzenkirchenHechtetal., author = {Kleshch, Victor I. and Serbun, Pavel and L{\"u}tzenkirchen-Hecht, Dirk and Orekhov, Anton S. and Ivanov, Victor E. and Prommesberger, Christian and Langer, Christoph and Schreiner, Rupert and Obraztsov, Alexander N.}, title = {A Comparative Study of Field Emission from Pristine, Ion-treated and Tungsten Nanoparticle-decorated p-type Silicon Tips}, series = {Physica Status Solidi B}, volume = {256}, journal = {Physica Status Solidi B}, number = {9}, publisher = {Wiley}, doi = {10.1002/pssb.201800646}, abstract = {The field electron emission characteristics of individual tips of a silicon field emitter array are analyzed. The array of conical-shaped tips is fabricated on a p-type silicon wafer by using reactive ion etching and sharpening oxidation. The tips are decorated with single tungsten nanoparticles at their apexes. Furthermore, the focused ion beam is also used to increase surface conductivity of some of the tips. Comparative measurements of field emission are performed by using the scanning anode probe field emission microscopy technique. All types of tips demonstrated emission activation consisting of a sudden current increase at a certain value of the applied voltage. Compared to the pristine tips, a noticeable reduction of the saturation effect in the current-voltage characteristics and a smaller light sensitivity for the decorated tips is found. For ion-treated tips, saturation effects and light sensitivity are completely suppressed. Scanning electron microscopy observations reveal the formation of single nanoscale protrusions extending from the metal particles and from the apexes of bare ion-treated tips after exposure under strong electric fields during the field emission measurements. The influence of protrusions growth on characteristics of silicon field emitter arrays is discussed.}, language = {en} } @article{LangerBomkeHausladenetal., author = {Langer, Christoph and Bomke, Vitali and Hausladen, Matthias and Ławrowski, Robert Damian and Prommesberger, Christian and Bachmann, Michael and Schreiner, Rupert}, title = {Silicon Chip Field Emission Electron Source Fabricated by Laser Micromachining}, series = {Journal of Vacuum Science \& Technology B}, volume = {38}, journal = {Journal of Vacuum Science \& Technology B}, number = {1}, publisher = {AIP Publishing}, doi = {10.1116/1.5134872}, abstract = {The components for a silicon chip electron source were fabricated by laser micromachining using pulsed laser ablation and wet chemical cleaning and etching dips. The field emission electron source consists of a silicon field emission cathode with 4 × 4 conical shaped emitters with a height of 250 μm and a tip radius of about 50 nm, a 50 μm thick laser-structured mica spacer, and a silicon grid electrode with a grid periodicity of 200 μm and a bar width of 50 μm. These three components are combined to a single chip with the size of 14 × 10 mm2 and the thickness of 1 mm to form the electron source. Several of these devices were characterized in ultrahigh vacuum. Onset voltages of about 165 V and cathode currents of about 15 μA for voltages lower than 350 V were observed. Operating the electron source with an anode voltage of 500 V and an extraction grid voltage of 300 V yielded a cathode current of 4.5 μA ± 8.9\%, an anode current of 4.0 μA ± 9.6\%, and a corresponding grid transmittance of 89\%. Regulating the anode current by the extraction grid voltage, an extremely stable anode current of 5.0 μA ± 0.017\% was observed. A long-term measurement over 120 h was performed, and no significant degradation or failure was observed.}, language = {en} } @article{BreuerBachmannDuesbergetal., author = {Breuer, Janis and Bachmann, Michael and D{\"u}sberg, Felix and Pahlke, Andreas and Edler, Simon and Langer, Christoph and Prommesberger, Christian and Ławrowski, Robert Damian and Schreiner, Rupert and Serbun, Pavel and L{\"u}tzenkirchen-Hecht, Dirk}, title = {Extraction of the current distribution out of saturated integral measurement data of p-type silicon field emitter arrays}, series = {Journal of Vacuum Science and Technology B}, volume = {36}, journal = {Journal of Vacuum Science and Technology B}, number = {5}, publisher = {AIP Publishing}, doi = {10.1116/1.5035189}, abstract = {At the moment, only complicated techniques are known for the determination of array properties of field emitter arrays such as the number of active tips, the current distribution, or the individual tip radii. In this work, a method for extracting these parameters from integral measurement data is presented. A model describing the characteristics of a single emitter, including the saturation as a function of the applied voltage and the emitter radius, is developed. It is shown that experimental data of field emitter arrays can be represented as the sum of these functions and the characteristic parameters can be fitted to field emission data of an array. Using this method, the values of the radii as well as the parameters of distribution models can be determined directly. Analysis of experimental data from p-type Si emitter arrays shows that only 1-2\% of the tips contribute significantly.}, language = {en} } @article{BachmannDamsDuesbergetal., author = {Bachmann, Michael and Dams, Florian and D{\"u}sberg, Felix and Hofmann, Martin and Pahlke, Andreas and Langer, Christoph and Ławrowski, Robert Damian and Prommesberger, Christian and Schreiner, Rupert and Serbun, Pavel and L{\"u}tzenkirchen-Hecht, Dirk and M{\"u}ller, G{\"u}nter}, title = {Extraction of the characteristics of current-limiting elements from field emission measurement data}, series = {Journal of Vacuum Science \& Technology B}, volume = {35}, journal = {Journal of Vacuum Science \& Technology B}, number = {2}, doi = {10.1116/1.4971768}, abstract = {In this contribution, the authors will present an algorithm to extract the characteristics of nonideal field emission circuit elements from saturation-limited field emission measurement data. The method for calculating the voltage drop on current-limiting circuit elements is based on circuit theory as well as Newton's method. Since the only assumption the authors make on the current-limiting circuit is a connection in series, this method is applicable to most field emission data showing saturation. To be able to determine the significance of any parameter output, the uncertainties of data and extracted parameters as well as the parameter correlations are fully taken into account throughout the algorithm. N-type silicon samples with varying external serial resistors are analyzed. All results show a good agreement to the nominal resistor values. Additionally, several p-type samples are analyzed, showing a diodelike behavior. The extracted current-limiting characteristics of the p-type samples are in good agreement with a pn-junction model. The stability of the emission current of the p-type samples is measured by constant voltage measurements and compared to the extracted current-limiting characteristics. The application of the algorithm to measurement data shows that the given algorithm is a valuable tool to analyze field emission measurement data influenced by nonemissive processes.}, language = {en} } @article{PrommesbergerBachmannDuesbergetal., author = {Prommesberger, Christian and Bachmann, Michael and D{\"u}sberg, Felix and Langer, Christoph and Ławrowski, Robert Damian and Hofmann, Martin and Pahlke, Andreas and Schreiner, Rupert}, title = {Regulation of the Transmitted Electron Flux in a Field-Emission Electron Source Demonstrated on Si Nanowhisker Cathodes}, series = {IEEE Transactions on Electron Devices}, volume = {64}, journal = {IEEE Transactions on Electron Devices}, number = {12}, issn = {5128-5133}, doi = {10.1109/TED.2017.2763239}, abstract = {We report on a method to stabilize the transmitted electron flux in a field-emission electron source using an external regulation circuit. The electron source was realized with an array of silicon (Si) nanowhiskers on the top of elongated pillar structures, a mica spacer, and an extraction grid made of Si. As for most applications, the emitted electron current from the cathode is not as crucial as the transmitted electron flux through the extraction grid toward the anode. We investigated a method which allows the regulation directly by the emitted electron flux and not merely on the cathode current. By using this method, we were able to stabilize the emitted electron flux of our electron source down to values below 1\%. Simultaneously, it was shown that there is the possibility to stabilize the influencing value in the real application as well. The effectiveness of this method was demonstrated successfully with an X-ray source setup. The measured X-ray photon count rate was stabilized to a standard deviation of 0.30\% at a pressure of 1 × 10 -7 mbar. Even in harsh environment of 2 × 10 -5 mbar, a stabilization of the X-ray photon count rate down to a value of 0.63\% was achieved.}, language = {en} } @article{MingelsPorshynPrommesbergeretal., author = {Mingels, S. and Porshyn, V. and Prommesberger, Christian and Langer, Christoph and Schreiner, Rupert and L{\"u}tzenkirchen-Hecht, Dirk and M{\"u}ller, G{\"u}nter}, title = {Photosensitivity of p-type black Si field emitter arrays}, series = {Journal of Applied Physics}, volume = {119}, journal = {Journal of Applied Physics}, number = {16}, doi = {10.1063/1.4948328}, abstract = {We have investigated the properties of black Si field emitter arrays under strong electric fields and laser illumination. A low onset field of 1.8 MV/m for an emission current of 1 nA was obtained. A pronounced saturation region of the dark and photo-enhanced current was observed, which provided a short-term stability of 0.1\% at 0.4 μA and 0.7\% at 1.0 μA, respectively. As maximum value for the photosensitivity, an on-off current switching ratio of 43 reaching about 13 μA was achieved at a laser power of 15 mW. Electron spectra in the dark and under laser illumination are presented, showing a current and light-sensitive voltage drop across the emitters as well as hints for hot electron emission.}, language = {en} } @misc{DuesbergBachmannEdleretal., author = {D{\"u}sberg, Felix and Bachmann, Michael and Edler, Simon and Pahlke, Andreas and Langer, Christoph and Prommesberger, Christian and Schreiner, Rupert and Bunert, Erik and Wendt, Cornelius and Zimmermann, Stefan}, title = {Novel Non-Radiative Electron Source}, series = {43rd International Symposium of Capillary Chromatography \& 16h GC x GC Symposium 2019}, journal = {43rd International Symposium of Capillary Chromatography \& 16h GC x GC Symposium 2019}, abstract = {Recently a non-radioactive electron capture detector based on a thermionic electron emitter has been demonstrated [1]. Using field emitter arrays (FEAs) would yield non-radioactive portable low power devices with fast switching capability. By combining FEAs with a vacuum-sealed housing and an electron transparent membrane window, such electron sources can be operated in an ambient pressure environment.}, language = {en} } @article{ŁawrowskiPrommesbergerLangeretal., author = {Ławrowski, Robert Damian and Prommesberger, Christian and Langer, Christoph and Dams, Florian and Schreiner, Rupert}, title = {Improvement of Homogenity and Aspect Ratio of Silicon Tips for Field Emission by Reactive-Ion Etching}, series = {Advances in materials science and engineering}, volume = {2014}, journal = {Advances in materials science and engineering}, publisher = {Hindawi}, doi = {10.1155/2014/948708}, abstract = {The homogeneity of emitters is very important for the performance of field emission (FE) devices. Reactive-ion etching (RIE) and oxidation have significant influences on the geometry of silicon tips. The RIE influences mainly the anisotropy of the emitters. Pressure has a strong impact on the anisotropic factor. Reducing the pressure results in a higher anisotropy, but the etch rate is also lower. A longer time of etching compensates this effect. Furthermore an improvement of homogeneity was observed. The impact of uprating is quite low for the anisotropic factor, but significant for the homogeneity. At low power the height and undercut of the emitters are more constant over the whole wafer. The oxidation itself is very homogeneous and has no observable effect on further variation of the homogeneity. This modified fabrication process allows solving the problem of inhomogeneity of previous field emission arrays.}, language = {en} } @inproceedings{LangerŁawrowskiPrommesbergeretal., author = {Langer, Christoph and Ławrowski, Robert Damian and Prommesberger, Christian and Dams, Florian and Serbun, Pavel and Bachmann, Michael and M{\"u}ller, G{\"u}nter and Schreiner, Rupert}, title = {High aspect ratio silicon tip cathodes for application in field emission electron sources}, series = {2014 27th International Vacuum Nanoelectronics Conference (IVNC), 6-10 July 2014, Engelberg, Switzerland}, booktitle = {2014 27th International Vacuum Nanoelectronics Conference (IVNC), 6-10 July 2014, Engelberg, Switzerland}, publisher = {IEEE}, doi = {10.1109/IVNC.2014.6894824}, pages = {222 -- 223}, abstract = {Precisely aligned arrays of sharp tip structures on top of elongated pillars were realized by using an improved fabrication process including an additional inductively-coupled-plasma reactive-ion etching step. Arrays of n-type and p-type silicon with 271 tips have been fabricated and investigated. Those structures have a total height of 5-6 µm and apex radii less than 20nm. Integral field emission measurements of the arrays yielded low onset-fields in the range of 8-12V=µm and field enhancement factors between 300 and 700. The I-E curves of n-type structures showed the usual Fowler-Nordheim behaviour, whereas p-type structures revealed a significant saturation region due to the limited number of electrons in the conduction band and a further carrier depletion effect caused by the pillar. The maximum integral current in the saturation region was 150 nA at fields above 30V=µm. An excellent stability of the emission current of less than ± 2\% fluctuation was observed in the saturation region. For n-type Si a maximum integral current of 10 µA at 24V=µm and an average current stability with a fluctuation of ± 50\% were measured.}, language = {en} } @inproceedings{MingelsPorshynSerbunetal., author = {Mingels, S. and Porshyn, V. and Serbun, Pavel and L{\"u}tzenkirchen-Hecht, Dirk and M{\"u}ller, G{\"u}nter and Prommesberger, Christian and Langer, Christoph and Schreiner, Rupert and Lutzenkirchen-Hecht, Dirk}, title = {Photo-enhanced field emission properties of p-doped black Si arrays}, series = {2016 29th International Vacuum Nanoelectronics Conference (IVNC), 11-15 July 2016, Vancouver, BC, Canada}, booktitle = {2016 29th International Vacuum Nanoelectronics Conference (IVNC), 11-15 July 2016, Vancouver, BC, Canada}, publisher = {IEEE}, doi = {10.1109/IVNC.2016.7551447}, pages = {1 -- 2}, abstract = {We have carried out systematic investigations of p-type black Si field emitter arrays under laser illumination. As expected the current-voltage characteristic revealed a strong saturation providing a high photosensitivity, which had a maximum on-off ratio of 43 at a maximum current of 13 μA. The saturation current was stable in the dark as well as under illumination with fluctuations <;0.7\%. Results from time-resolved measurements of the photo-sensitivity showed a rather fast response but a long decay time. Electron spectra in the dark and under laser illumination revealed the origin of the emission.}, language = {en} } @inproceedings{BiekerRoustaieSchlaaketal., author = {Bieker, Johannes and Roustaie, Farough and Schlaak, H. F. and Langer, Christoph and Schreiner, Rupert}, title = {Field emission characterization of in-situ deposited metallic nanocones}, series = {2017 30th International Vacuum Nanoelectronics Conference (IVNC), 10-14 July 2017, Regensburg, Germany}, booktitle = {2017 30th International Vacuum Nanoelectronics Conference (IVNC), 10-14 July 2017, Regensburg, Germany}, publisher = {IEEE}, doi = {10.1109/IVNC.2017.8051571}, pages = {120 -- 121}, abstract = {An in-situ fabrication technique based on ion track etched template electrodeposition of metallic nanocones was used for the production of field emitter cathodes. Gold nanocones with a height of 24 microns, a base diameter between 3 to 4 microns and a tip diameter below 300 nanometers were deposited on a circular electrode with a diameter of 2.5 mm. The integral field emission (FE) measurements of samples with cone densities of 6 · 104 cones/cm2 (sample A) and 1 · 106 cones/cm2 (sample B) yielded in a maximum current of 37.5 μA at an applied field of 12.5 V/μm for sample A and 29.1 μA at 9.4 V/μm for sample B. The stability of emission current was investigated for over 48 hours and no degradation was observed.}, language = {en} } @inproceedings{PrommesbergerLangerŁawrowskietal., author = {Prommesberger, Christian and Langer, Christoph and Ławrowski, Robert Damian and Muller, F. and Dams, Florian and Schreiner, Rupert and Serbun, Pavel and M{\"u}ller, G{\"u}nter}, title = {Comparison of integral and local field-emission properties of Mo-coated p-Si tip arrays}, series = {2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China}, booktitle = {2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China}, publisher = {IEEE}, doi = {10.1109/IVNC.2015.7225579}, pages = {192 -- 193}, abstract = {Silicon tip arrays were fabricated by means of reactive ion etching followed by oxidation for final sharpening and molybdenum thin film coating. The field-emission (FE) properties of these Mo-coated p-Si tip arrays were systemically investigated by different measurement techniques. Integral measurements in diode configuration yielded a turn-on field (for 1 nA) of 22 V/μm and nearly stable FE currents up to 6.6 μA at 38 V/μm. The effective field enhancements factor extracted from the FN plots is about 180. Detailed investigations of these FE arrays were also performed by means of field emission scanning microscopy combined with electron microscopy. A rather limited efficiency of the tips (50\% at 1500 V) and FE homogeneity (180 nA at 700 V) might be correlated with the varying morphology of the tips and the presence of oxides. Local I-V measurements of selected single tips revealed both activation and deactivation effects, which finally resulted in nearly reproducible I-V curves. Current stability measurements at a constant voltage showed rather large fluctuations (0.1-1 μA) of the FE current, which could be reduced up to 1.7\% by using of a PID-regulated voltage source. SEM images showed unchanged tip shape after the current processing.}, language = {en} } @article{SerbunBornmannNavitskietal., author = {Serbun, Pavel and Bornmann, Benjamin and Navitski, Aliaksandr and M{\"u}ller, G{\"u}nter and Prommesberger, Christian and Langer, Christoph and Dams, Florian and Schreiner, Rupert}, title = {Stable field emission of single B-doped Si tips and linear current scaling of uniform tip arrays for integrated vacuum microelectronic devices}, series = {Journal of Vacuum Science \& Technology B Nanotechnology and Microelectronics}, volume = {31}, journal = {Journal of Vacuum Science \& Technology B Nanotechnology and Microelectronics}, number = {2}, publisher = {AIP Publishing}, doi = {10.1116/1.4765088}, abstract = {Advanced Si-based semiconductor technology is most suitable to fabricate uniform nanostructures as integrated field emitter arrays for novel vacuum electronic devices. In order to improve the field emission homogeneity and stability of p-type silicon tip arrays for pulsed sensor applications, the authors have systematically studied the influence of the fabrication parameters on the tip shape and on the specific operating conditions. Based on detailed design calculations of the field enhancement, they have fabricated two series of hexagonal arrays of B-doped Si-tips in a triangular arrangement. The first (second) type contains three (four) patches with different number of tips (1, 91, 547 and 1, 19, 1027, 4447 for the first and second type, respectively) of about 1 (2.5) μm height, ∼20 (20) nm apex radius, and 20 (10) μm pitch. The field emission properties of both individual tips and complete arrays were investigated with a field emission scanning microscope at a pressure of 10-9 mbar. The current plateau of these tips typically occurs at about 10 (3) nA and around 65 (25) V/μm field level. In this carrier saturation range, single tips provide the highest current stability (<5\%) and optical current switching ratio (∼2.5). Fairly homogeneous emission of the tip arrays leads to an undershooting of the expected linear scaling of the mean plateau current as well as to a much improved current stability (<1\%).}, language = {en} } @inproceedings{ŁawrowskiLangerPrommesbergeretal., author = {Ławrowski, Robert Damian and Langer, Christoph and Prommesberger, Christian and Schreiner, Rupert and Mingels, S. and Porshyn, V. and Serbun, Pavel and M{\"u}ller, G{\"u}nter}, title = {Field emission from surface textured GaN with buried double-heterostructures}, series = {2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China}, booktitle = {2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China}, publisher = {IEEE}, doi = {10.1109/IVNC.2015.7225548}, pages = {106 -- 107}, abstract = {In this contribution we report on field emission (FE) cathodes based on thin-film LED-technology and surface texturing. The FE cathode can be used both as an n-GaN cathode with an electrical contact at the top side metallization as well as a pn-GaN diode contacting only the p-GaN layer at the bottom side of the structure. The local and integral FE properties of the textured surface of the LED structure were investigated. For n-GaN an integral emission current up to 1.0 μA at an electric field of 19 V/μm was achieved. The pn-GaN diode measurements showed an integral current saturation behavior with two orders of magnitude lower FE currents. Regulated voltage scans obtained by FE scanning microscopy revealed a well-distributed emission over the whole cathode area. Measurements under pulsed tunable laser illumination and moderate electric fields indicated charge carrier generation in the buried double-heterostructures at photon energies below 3.5 eV besides normal photoemission above 4.1 eV.}, language = {en} } @inproceedings{LangerPrommesbergerŁawrowskietal., author = {Langer, Christoph and Prommesberger, Christian and Ławrowski, Robert Damian and M{\"u}ller, F. and Schreiner, Rupert and Serbun, Pavel and M{\"u}ller, G{\"u}nter}, title = {Enhanced field emission from p-doped black silicon on pillar structures}, series = {2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China}, booktitle = {2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China}, publisher = {IEEE}, doi = {10.1109/IVNC.2015.7225547}, pages = {104 -- 105}, abstract = {Aligned square arrays of black silicon (b-Si) on top of pillars were fabricated on p-type silicon substrate by a deep-etching step combined with a b-Si process. Two 10×10 arrays with pillar heights of 8 μm and 20 μm and one b-Si reference sample without pillars were investigated. Integral field emission (FE) measurements of the arrays yielded rather low onset-fields between 6.4 V/μm and 13.5 V/μm and field enhancement factors between 430 and 800. The I-V curves showed typical Fowler-Nordheim behavior for low fields, whereas a saturation region was observed at higher fields. The maximum integral current in the saturation region was 8 μA at a field of 20 V/μm. The stability of the emission current was investigated over 3 hours and revealed moderate fluctuations of ± 8\% in the saturation region. Voltage scans showed well-aligned FE from nearly all pillars.}, language = {en} } @inproceedings{KleshchSerbunOrekhovetal., author = {Kleshch, Victor I. and Serbun, Pavel and Orekhov, Anton and L{\"u}tzenkirchen-Hecht, Dirk and Obraztsov, Alexander N. and Prommesberger, Christian and Langer, Christoph and Schreiner, Rupert and Lutzenkirchen-Hecht, Dirk}, title = {Field emission properties of p-type silicon tips decorated with tungsten nanoparticles}, series = {2017 30th International Vacuum Nanoelectronics Conference (IVNC), 10-14 July 2017, Regensburg, Germany}, booktitle = {2017 30th International Vacuum Nanoelectronics Conference (IVNC), 10-14 July 2017, Regensburg, Germany}, publisher = {IEEE}, doi = {10.1109/IVNC.2017.8051580}, pages = {138 -- 139}, abstract = {An array of conical-shaped p-type silicon tips was fabricated by using reactive ion etching and sharpening oxidation. The apex of each tip was decorated by a tungsten hemispherical nanoparticle. Field emission properties of the tips were measured by a tungsten-needle anode positioned above the tip apex. Tips decorated with tungsten nanoparticles demonstrated a smaller saturation region in current-voltage characteristics compared to the pristine tips. An emission activation process, which consisted in sudden current increase at certain value of applied voltage, was observed for the decorated silicon tips. This behavior was explained by the formation of vertical protrusions extending from the metal particles revealed by scanning electron microscopy after field emission experiments.}, language = {en} } @article{LangerPrommesbergerŁawrowskietal., author = {Langer, Christoph and Prommesberger, Christian and Ławrowski, Robert Damian and Dams, Florian and Schreiner, Rupert}, title = {Simulation and Fabrication of Silicon Field Emission Cathodes for Cold Electron Sources}, series = {Advanced Materials Research}, volume = {1024}, journal = {Advanced Materials Research}, doi = {10.4028/www.scientific.net/amr.1024.48}, pages = {48 -- 51}, abstract = {We report on the simulation and fabrication of nanostructured silicon surfaces for field emission (FE) applications, e.g. ionization sensors and x-ray tubes. For the design and optimization of field-emitting silicon structures, the influence of the geometric parameters like tip height, apex radius, aperture angle and curvature shape on the field enhancement factor was investigated by simulation using finite element method. A universal geometric model which describes the real geometry of our silicon structures sufficiently accurate was taken for modeling a variety of different silicon tip structures as well as ridge structures. While a high dependency of the field enhancement on the aspect ratio and the aperture angle was found, the simulations show that the elliptic curvature affects the field enhancement only marginally. Finally, an improved process for fabrication of such silicon structures on n-type as well as p-type substrate is described, using reactive ion etching with adjustable anisotropy, wet thermal oxidation and wet etching.}, language = {en} } @inproceedings{MingelsBornmannLuetzenkirchenHechtetal., author = {Mingels, Stephan and Bornmann, Benjamin and L{\"u}tzenkirchen-Hecht, Dirk and M{\"u}ller, G{\"u}ntner and Langer, Christoph and Prommesberger, Christian and Schreiner, Rupert}, title = {Electric Field Dependence of Photoemission from n- and p-type Si Crystals}, series = {Proceedings, 35th International Free Electron Laser Conference (FEL 2013) : New York, NY, USA, August 26-19, 2013}, booktitle = {Proceedings, 35th International Free Electron Laser Conference (FEL 2013) : New York, NY, USA, August 26-19, 2013}, editor = {Scholl, Caitlin and Schaa, Volker R.W.}, publisher = {Curran}, address = {Red Hook, NY}, isbn = {9783954501267}, pages = {339 -- 343}, abstract = {The performance of free electron lasers depends on the brilliance of the electron source. Nowadays photo-cathodes (e.g. Cs2Te) are used despite of their high emittance. To develop robust and more brilliant cathodes we have built up an UHV system which enables systematic photoemission (PE) measurements with a tunable pulsed laser (hv) at high electric fields (E). First results on Au and Ag crystals revealed only low quantum efficiency (QE) due to fast electron relaxation. Hence, we have started QE(hv,E) investigations on n- and p-Si wafers. Resonant PE was observed above as well as below the work function O, which can be assigned to optical transitions in the electronic band structure or explained by thermally excited states at the bottom of the conduction band. As expected, only low QE values were achieved even for n-Si probably due to surface oxide. Moreover, a significant rise of the QE peaks above O were obtained for n-Si at E >8 MV/m but limited by the occurrence of parasitic field emission from dust particles.}, language = {en} } @article{ŁawrowskiPrommesbergerLangeretal., author = {Ławrowski, Robert Damian and Prommesberger, Christian and Langer, Christoph and Dams, Florian and Schreiner, Rupert}, title = {Improvement of Homogeneity and Aspect Ratio of Silicon Tips for Field Emission by Reactive-Ion Etching}, series = {Advances in Materials Science and Engineering. Special issue: Advances in Smart Materials and Applications}, volume = {2014}, journal = {Advances in Materials Science and Engineering. Special issue: Advances in Smart Materials and Applications}, publisher = {Hindawi}, issn = {1687-8442}, doi = {10.1155/2014/948708}, pages = {1 -- 6}, abstract = {The homogeneity of emitters is very important for the performance of field emission (FE) devices. Reactive-ion etching (RIE) and oxidation have significant influences on the geometry of silicon tips. The RIE influences mainly the anisotropy of the emitters. Pressure has a strong impact on the anisotropic factor. Reducing the pressure results in a higher anisotropy, but the etch rate is also lower. A longer time of etching compensates this effect. Furthermore an improvement of homogeneity was observed. The impact of uprating is quite low for the anisotropic factor, but significant for the homogeneity. At low power the height and undercut of the emitters are more constant over the whole wafer. The oxidation itself is very homogeneous and has no observable effect on further variation of the homogeneity. This modified fabrication process allows solving the problem of inhomogeneity of previous field emission arrays.}, language = {en} } @inproceedings{SchreinerLangerPrommesbergeretal., author = {Schreiner, Rupert and Langer, Christoph and Prommesberger, Christian and Mingels, S. and Serbun, Pavel and M{\"u}ller, G{\"u}ntner}, title = {Field emission from surface textured extraction facets of GaN light emitting diodes}, series = {26th International Vacuum Nanoelectronics Conference (IVNC), 8-12 July 2013, Roanoke, VA, USA}, booktitle = {26th International Vacuum Nanoelectronics Conference (IVNC), 8-12 July 2013, Roanoke, VA, USA}, publisher = {IEEE}, doi = {10.1109/ivnc.2013.6624721}, abstract = {We report on the field emission properties of GaN LED surfaces. The textured extraction facet acts both as light scattering layer in order to increase the light extraction efficiency of the LED as well as nanostructured cathode surface for the field emission (FE) of electrons. The LED emits blue light with a peak wavelength of around 450 nm. The FE properties were investigated by a scanning microscope. Integral measurements as well as regulated voltage scans for 1 nA FE current over an area of 400 * 400 µm2were used to investigate both overall and local FE properties. A high number of well-distributed emitters with an average field enhancement factor ß of 85 and stable integral emission currents up to 100 µA at an electric field of   80 V/µm ({\O}anode= 880 µm) were found. Photo-field-emission spectroscopy (PFES) using a tunable pulsed laser revealed an enhanced photo absorption of the InGaN/GaN quantum well structures near the emission wavelength of the LED (<3.5 eV), whereas at high photon energies (>4.1 eV) photoemission from the GaN surface was observed.}, language = {en} } @article{DamsNavitskiPrommesbergeretal., author = {Dams, Florian and Navitski, Aliaksandr and Prommesberger, Christian and Serbun, Pavel and Langer, Christoph and M{\"u}ller, G{\"u}nter and Schreiner, Rupert}, title = {Homogeneous Field Emission Cathodes With Precisely Adjustable Geometry Fabricated by Silicon Technology}, series = {IEEE Transactions on Electron Devices}, volume = {59}, journal = {IEEE Transactions on Electron Devices}, number = {10}, publisher = {IEEE}, issn = {0018-9383}, doi = {10.1109/TED.2012.2206598}, pages = {2832 -- 2837}, abstract = {Silicon-based cathodes with precisely aligned field emitter arrays of sharp tips applicable for miniaturized electron sources were successfully fabricated and characterized. This was made possible by an improved fabrication process using wet thermal oxidation, wet etching, and reactive-ion etching steps with adjustable anisotropy. As substrate materials, both p-doped silicon and n-doped silicon were used. The cathode chips contain about 3 × 10 5 Si tips/cm 2 in a triangular array with tip heights of 2.5 μm, tip radii of less than 30 nm, and spacing of 20 μm. Well-aligned field emission (FE) and excellent homogeneity from all tips (i.e., 100\% efficiency) and maximum stable currents of typically 0.1 μA (0.6 μA) for p (n)-type Si were reproducibly achieved. The current-voltage characteristics of the p-Si tips exhibit the expected saturation at around 10 nA with around ten times better current stability, whereas the n-Si tips show the usual Fowler-Nordheim behavior. Additional coating of the Si tips with 5-nm Cr and 10-nm Au layers resulted in improved stability and at least five times higher average FE current limits (about 3 μA) at about 30\% higher operation voltage.}, language = {en} } @inproceedings{BornmannMingelsSerbunetal., author = {Bornmann, Benjamin and Mingels, Stephan and Serbun, Pavel and L{\"u}tzenkirchen-Hecht, Dirk and M{\"u}ller, G{\"u}ntner and Prommesberger, Christian and Langer, Christoph and Dams, Florian and Schreiner, Rupert}, title = {Photosensitivity of electron field emission from B-doped Si-tip arrays}, series = {25th International Vacuum Nanoelectronics Conference (IVNC) ; Jeju, Korea (South), 09.07.2012 - 13.07.2012}, booktitle = {25th International Vacuum Nanoelectronics Conference (IVNC) ; Jeju, Korea (South), 09.07.2012 - 13.07.2012}, publisher = {IEEE}, isbn = {978-1-4673-1984-3}, issn = {2380-6311}, doi = {10.1109/IVNC.2012.6316980}, pages = {1 -- 2}, abstract = {The electron current from field-emitting B-doped Si-tip arrays under illumination was studied. An improved cathode design with a patch of 271 tips yielded a reproducible cathode current between 0.2-2000 nA in the electric field range of 3.8-6.6 V/μm. The plateau in the Fowler-Nordheim plot shows the actual carrier depletion and leads to a very stable emission at ~1 μA with a current noise of less than 3.3 \%. Color-filtered halogen lamp illumination was used to investigate the photo-sensitivity of the saturation current. The intensity-normalized current switching ratio increases nonlinearly with the photon energy. This hints either for secondary generation in the conduction band or deeper valence band excitation. The first is supported by a rough estimation of the quantum efficiency. Further experiments with a tunable laser and electron spectroscopy are planned.}, language = {en} } @inproceedings{LangerPrommesbergerDamsetal., author = {Langer, Christoph and Prommesberger, Christian and Dams, Florian and Schreiner, Rupert}, title = {Theoretical investigations into the field enhancement factor of silicon structures}, series = {25th International Vacuum Nanoelectronics Conference (IVNC) - Jeju, Korea (South), 09.- 13.07.2012}, booktitle = {25th International Vacuum Nanoelectronics Conference (IVNC) - Jeju, Korea (South), 09.- 13.07.2012}, publisher = {IEEE}, address = {Piscataway, N.J.}, isbn = {978-1-4673-1984-3}, issn = {2380-6311}, doi = {10.1109/IVNC.2012.6316886}, abstract = {In order to optimize our field-emitting silicon structures, the influence of geometric parameters like aspect ratio, aperture angle and curvature on the field enhancement factor was investigated by finite element simulations. A universal geometric model consisting of a rounded triangle and elliptic curvatures was taken for modeling a variety of different silicon tip as well as ridge structures. Whereas, a high dependency of the field enhancement on the aperture angle was found, the simulations show that the elliptic curvature affects the field enhancement only marginal.}, language = {en} } @inproceedings{ŁawrowskiPrommesbergerLangeretal., author = {Ławrowski, Robert Damian and Prommesberger, Christian and Langer, Christoph and Dams, Florian and Schreiner, Rupert}, title = {Influence of reactive ion etching parameters on the geometry of silicon tip cathodes for field emission}, series = {Applied Research Conference 2013, ARC 2013 : 17th and 18th October 2013, Deggendorf}, booktitle = {Applied Research Conference 2013, ARC 2013 : 17th and 18th October 2013, Deggendorf}, publisher = {Shaker}, address = {Aachen}, isbn = {978-3-8440-2274-2}, pages = {67 -- 69}, language = {en} } @inproceedings{SchreinerPrommesbergerLangeretal., author = {Schreiner, Rupert and Prommesberger, Christian and Langer, Christoph and Dams, Florian and Serbun, Pavel and Bornmann, Benjamin and Navitski, Aliaksandr and M{\"u}ller, G{\"u}ntner}, title = {Highly uniform and stable electron field emission from B-doped Si-tip arrays for applications in integrated vacuum microelectronic devices}, series = {25th International Vacuum Nanoelectronics Conference (IVNC) - Jeju, Korea (South), 09.07. - 13.07.2012}, booktitle = {25th International Vacuum Nanoelectronics Conference (IVNC) - Jeju, Korea (South), 09.07. - 13.07.2012}, publisher = {IEEE}, address = {Piscataway, NJ.}, isbn = {978-1-4673-1984-3}, issn = {2380-6311}, doi = {10.1109/IVNC.2012.6316857}, pages = {1 -- 2}, abstract = {In order to improve the uniformity and field emission stability of p-type silicon tip arrays for pulsed sensor applications, we have systematically studied the influence of the fabrication parameters on the tip shape and the specific operating conditions. Based on detailed design calculations of the field enhancement, we have fabricated a series of hexagonal arrays of B-doped Si-tips in a triangular arrangement, each containing a different number of tips (91, 575 and 1300) of 1 μm height, 20 nm apex radius, and 20 μm pitch. The field emission properties of both individual tips and complete arrays were investigated with by field emission scanning microscopy. The current plateaus of these tips typically occur at about 10 nA and 60 V/μm field level. In this carrier depletion range, single tips provide the highest current stability (<; 4\%) and optical current switching ratios of ~2.5. Rather homogeneous emission of the tip arrays leads to an almost linear scaling of the saturation current (2 nA/tip) and to a much improved current stability (<; 1\%) measured over 1 hour.}, language = {en} } @inproceedings{SerbunNavitskiMuelleretal., author = {Serbun, Pavel and Navitski, Aliaksandr and M{\"u}ller, G{\"u}ntner and Schreiner, Rupert and Prommesberger, Christian and Langer, Christoph and Dams, Florian}, title = {Scaling of the field emission current from B-doped Si-tip arrays}, series = {25th International Vacuum Nanoelectronics Conference (IVNC) ; Jeju, Korea (South), 09.07.2012 - 13.07.2012}, booktitle = {25th International Vacuum Nanoelectronics Conference (IVNC) ; Jeju, Korea (South), 09.07.2012 - 13.07.2012}, publisher = {IEEE}, address = {Piscataway, N.J.}, isbn = {978-1-4673-1984-3}, issn = {2380-6311}, doi = {10.1109/IVNC.2012.6316965}, pages = {1 -- 2}, abstract = {We have fabricated a test chip with various hexagonal arrays of B-doped Si tips (height ~ 3 μm, apex radius <; 30 nm, number 1-4447, resistivity 4 Ωcm, 100 orientation) in triangular arrangement (pitch 10 μm, density 1.16×10 6 cm -2 ) in order to systematically investigate the field emission current scaling with the number N of tips. Regulated voltage scans for 1 nA revealed rather efficient emission from nearly all tips of the arrays at an average field of 15 V/μm. The expected current plateau was always obtained at fields around 20 V/μm, but its width strongly increased with N. In this carrier depletion range, the single tip provided a much higher stability (<; 5\%) of the current (2-3 nA) than at lower (>; 50 \%) and higher currents (>; 30\%). Integral current measurements of the hexagonal arrays resulted in a statistically improved current stability (<; 1\%) but only a weak increase of the total current with N 0.28 yet. These results will be discussed with respect to the remaining inhomogeneity of the tips.}, language = {en} } @inproceedings{SerbunPorshynMuelleretal., author = {Serbun, Pavel and Porshyn, V. and M{\"u}ller, G{\"u}nter and L{\"u}tzenkirchen-Hecht, Dirk and Prommesberger, Christian and Langer, Christoph and Ławrowski, Robert Damian and Schreiner, Rupert}, title = {Field emission behavior of single n- and p-type black Si pillar structures}, series = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, publisher = {IEEE}, doi = {10.1109/IVNC.2018.8520292}, pages = {1-2}, abstract = {We have investigated the properties of single n- and p-type black silicon (b-Si) pillars with a height of 20 μ m under strong electric field and halogen lamp or laser illumination. For both type of b-Si pillar structures, I-V measurements revealed strong activation effects, which consisted in sudden current increases during the first up/down voltage sweeps. The maximum reproducible emission current from a single n-type b-Si pillar structure was about 15 μ A. A pronounced saturation region at 240 nA was observed for a single p-type b-Si pillar. The current fluctuation over time showed a standard deviation of 28\% and 2.5\% for n- and p-type single b-Si pillar structures, respectively. Optical switching under halogen lamp illumination resulted in at least 3 times higher saturation currents and showed a linear dependence of the FE current on the laser power.}, language = {en} } @inproceedings{ŁawrowskiLangerPrommesbergeretal., author = {Ławrowski, Robert Damian and Langer, Christoph and Prommesberger, Christian and Schreiner, Rupert}, title = {Microrods and microlines by three-dimensional epitaxially grown GaN for field emission cathodes}, series = {International Vacuum Nanoelectronics Conference (IVNC), 30th, 2017, Regensburg}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 30th, 2017, Regensburg}, publisher = {IEEE}, doi = {10.1109/IVNC.2017.8051576}, pages = {130 -- 131}, abstract = {The three-dimensional epitaxial technique allows the realization of gallium nitride lines in addition to the rods. To optimize the properties of GaN-based field emission cathodes further investigations and an improvement of the epitaxial process were performed. The microrods and microlines consist of a one-order higher n-doped gallium nitride in comparison to the gallium nitride layer on the sapphire substrate. The typical height of the microrods and -lines is about 5 μm. The field emission properties of these structures were investigated in diode configuration by integral field emission measurements at pressures below 10 -9 mbar. For the microrods (microlines) a voltage of 1100 V (2000 V) was measured for a field emission current of about 0.5 μA with an onset field of about 12 MV/m (24 MV/m). Furthermore, the field enhancement factors for microrods and -lines are in the range of 300 and 200, respectively.}, language = {en} } @inproceedings{SerbunPorshynLuetzenkirchenHechtetal., author = {Serbun, Pavel and Porshyn, V. and L{\"u}tzenkirchen-Hecht, Dirk and Prommesberger, Christian and Langer, Christoph and Ławrowski, Robert Damian and Schreiner, Rupert}, title = {Photosensitivity of single silicon high-aspect-ratio tips with different doping levels}, series = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, publisher = {IEEE}, doi = {10.1109/IVNC.2018.8520288}, pages = {1-2}, abstract = {Photosensitivity of single lightly p-doped, highly p-doped, with an integrated p/n junction and intrinsic high-aspect-ratio (HAR) silicon tips was investigated in an ultra-high vacuum environment. The current-voltage characteristics (I-V) of the lightly doped p-type HAR tips showed a characteristic current saturation at around 10-12 nA, whereas the HAR Si tips with p/n junction showed similar saturation phenomena, however, at much smaller current values starting at ~20-30 pA. Optical switching under a halogen lamp illumination resulted in at least 2-4 times higher saturation currents and showed a linear dependence between the illumination power and the FE current, for both types of structures. In case of the highly p-doped HAR tips optical current switching effects, i. e. current saturation, were observed at rather low current levels 1-2 pA. Intrinsic HAR Si-tips showed relative unstable field emission behavior without a clear evidence of the photosensitivity.}, language = {en} } @inproceedings{LangerHausladenPrommesbergeretal., author = {Langer, Christoph and Hausladen, Matthias and Prommesberger, Christian and Ławrowski, Robert Damian and Bachmann, Michael and D{\"u}sberg, Felix and Pahlke, Andreas and Shamonin (Chamonine), Mikhail and Schreiner, Rupert}, title = {Field emission current investigation of p-type and metallized silicon emitters in the frequency domain}, series = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, publisher = {IEEE}, doi = {10.1109/IVNC.2018.8520127}, pages = {1-2}, abstract = {We investigated two different field emitter arrays consisting of 10×10 p-type and 10×10 undoped Au-coated high aspect ratio silicon tips. The I-V characterization of the p-type sample showed a pronounced saturation for voltages higher than 500 V and a maximum emission current of 39 nA. The metallized sample revealed a FN-like emission up to several μA. The metallized and the p-type sample operating below the saturation region showed high current fluctuations of ±16\%. Whereas, the metallized sample with current regulation and the p-type sample in the saturation yielded a current stability of ±0.4\% and ±0.3\%, respectively. Investigations in the frequency domain revealed the for field emission typical 1/f-noise. By operating in the saturation region (p-type sample) or using an emission current regulation (metallized sample) the noise level was reduced by at least 20 dB. Finally, the p-type sample was illuminated by a light emitting diode to increase and modulate the emission current in the saturation region. The emission current was increased by a factor of 3.7 to 145 nA. With this configuration we emulated an unstable emission behavior and evaluated the performance of our emission current regulation circuit.}, language = {en} } @inproceedings{BachmannDamsDuesbergetal., author = {Bachmann, Michael and Dams, Florian and D{\"u}sberg, Felix and Hofmann, Martin and Pahlke, Andreas and Langer, Christoph and Ławrowski, Robert Damian and Prommesberger, Christian and Schreiner, Rupert}, title = {Extraction of the characteristics of limiting elements from field emission measurement data}, series = {29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada}, booktitle = {29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada}, publisher = {IEEE}, issn = {2380-6311}, doi = {10.1109/IVNC.2016.7551474}, pages = {81 -- 82}, abstract = {In this contribution we will present an algorithm to extract the characteristics of non-Fowler-Nordheim (FN) circuit elements from saturation limited field emission (FE) measurement data. The method for calculating the voltage drop on limiting circuit elements is based on circuit theory as well as Newton's method. Since no assumption on the limiting circuit is made, this method is applicable to any FE data showing saturation. To be able to determine the significance of any parameter output, the uncertainties of data and extracted parameters are fully taken into account throughout the algorithm. External serial resistors and a limiting p-doped substrate are analyzed, where the latter shows a diode-like behavior.}, language = {en} } @inproceedings{BachmannDamsDuesbergetal., author = {Bachmann, Michael and Dams, Florian and D{\"u}sberg, Felix and Hofmann, Martin and Pahlke, Andreas and Langer, Christoph and Ławrowski, Robert Damian and Prommesberger, Christian and Schreiner, Rupert}, title = {Control of the electron source current}, series = {International Vacuum Nanoelectronics Conference (IVNC), 30th, 2017, Regensburg}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 30th, 2017, Regensburg}, publisher = {IEEE}, doi = {10.1109/IVNC.2017.8051550}, pages = {66 -- 67}, abstract = {A control circuit to stabilize the flux of electrons transmitted through an extractor electrode is presented. By controlling the emission current a fluctuation with a standard deviation of 0.015\% is observed. However, the achievable stability of the transmitted electron current is limited due to a variation of the extraction grid current ratio showing a standard deviation of 4.33\%. By regulating the difference of the emission current and the extraction grid current an improved stability of the transmitted electron current down to a standard deviation of 0.280\% is observed. Even with operation at 2 × 10 -5 mbar a standard deviation of 0.558\% is achieved.}, language = {en} } @inproceedings{PrommesbergerŁawrowskiLangeretal., author = {Prommesberger, Christian and Ławrowski, Robert Damian and Langer, Christoph and Dams, Florian and Schreiner, Rupert}, title = {Realisierung von Siliziumspitzenarrays mit integrierter Gate-Elektrode f{\"u}r Anwendungen in der Vakuumsensorik}, series = {4. Landshuter Symposium Mikrosystemtechnik, Mikrosystemtechnik als Schl{\"u}sseltechnologie der Systemintegration, Tagungsband zum Symposium 12./13. M{\"a}rz 2014, Hochschule Landshut}, booktitle = {4. Landshuter Symposium Mikrosystemtechnik, Mikrosystemtechnik als Schl{\"u}sseltechnologie der Systemintegration, Tagungsband zum Symposium 12./13. M{\"a}rz 2014, Hochschule Landshut}, address = {Landshut}, isbn = {978-3-9812696-5-9}, pages = {36 -- 41}, abstract = {Bei der Feldemission (kalte Emission) k{\"o}nnen Elektronen durch ein starkes elektrisches Feld eine glatte und leitende Oberfl{\"a}che verlassen. Die Elektronen tunneln dabei durch eine Potentialbarriere, deren Breite durch ein {\"a}ußeres elektrisches Feld verkleinert wird. Durch das Hinzuf{\"u}gen einer integrierten Gate-Elektrode um eine Siliziumspitze kann die notwendige Einsatzspannung f{\"u}r Feldemission deutlich gesenkt werden. Zwischen Si-Kathode und Gate-Elektrode befindet sich dabei eine Isolationsschicht, die h{\"o}chste Anforderungen bez{\"u}glich der elektrischen Durchbruchsfestigkeit erf{\"u}llen muss. Mit einer Kombination aus Trocken- (Schichtdicke 50 nm) und Feuchtoxid (Schichtdicke 950 nm) konnte eine Isolationsschicht entwickelt werden, die im integrierten Aufbau eine minimale Durchbruchsfeldst{\"a}rke von 3,2 MV/cm aufweist. F{\"u}r die Realisierung von Siliziumkathoden mit integrierter Gate-Elektrode wurde ein bereits bestehender Herstellungsprozess um zus{\"a}tzliche Prozessschritte erweitert. Die {\"U}bertragung der lateralen Position der Spitze erfolgt durch Strukturierung des Umkehrlacks AZ5214 und einer RIE-{\"A}tzung der zuvor hergestellten SiO2-Schicht. Nach dem Entfernen der Lackschicht wird die vertikale Struktur der Siliziumspitzen durch einen RIE-{\"A}tzprozess mit den Prozessgasen SF6 und O)2 realisiert. Aus einer thermischen Oxidation bei 940 °C resultiert anschließend die Isolationsschicht zwischen Si-Kathode und Gate-Elektrode . Gleichzeitig wird diese Ansch{\"a}rfeoxidation auch zur Realisierung der endg{\"u}ltigen Spitzengeometrie verwendet. Durch die lithographische Strukturierung des Photolacks AZ5214 kann dabei die Fl{\"a}che der aufgedampften Gate-Elektrode festgelegt werden. Die Gate-Elektrode wird in einem selbstjustierenden Prozessschritt exakt konzentrisch um die Si-Spitze aufgedampft. Der gerichtete Aufdampfprozess bewirkt eine Abschattung, so dass das Oxidpl{\"a}ttchen nicht komplett von Metall ummantelt wird. Die Opferschicht aus Photolack wird mit den nicht ben{\"o}tigten Metallfl{\"a}chen in einem Lift-off-Prozess entfernt.}, language = {de} } @inproceedings{PrommesbergerŁawrowskiLangeretal., author = {Prommesberger, Christian and Ławrowski, Robert Damian and Langer, Christoph and Mecani, Mirgen and Huang, Yifeng and She, Juncong and Schreiner, Rupert}, title = {Field emission properties of ring-shaped Si ridges with DLC coating}, series = {Proc. SPIE 10248, Nanotechnology VIII, 102480H (30 May 2017)}, volume = {102480H}, booktitle = {Proc. SPIE 10248, Nanotechnology VIII, 102480H (30 May 2017)}, editor = {Tiginyanu (Ed.), Ion M.}, publisher = {Society of Photo-Optical Instrumentation Engineers (SPIE)}, doi = {10.1117/12.2265627}, abstract = {We report on the fabrication and the emission characterization of single ring-shaped Si ridges with a coating of diamond-like carbon (DLC). The reactive ion etching and the subsequent inductively coupled plasma step were adjusted to realize ring-shaped Si ridges with a height of 7.5 μm respectively 15 μm and an apex radius of 20 - 25 nm. The samples were coated with a DLC layer (thickness ≈ 2 - 5 nm) by a filtered cathodic vacuum arc deposition system in order to lower the work function of the emitter and to improve the field emission characteristics. The field emission characterizations were done in diode configuration with cathode and anode separated by a 50 μm thick mica spacer. A higher emission current was carried out for the ring-shaped Si ridge in comparison to the point-shaped Si tips due to the increased emission area. The highest emission current of 0.22 μA at 1000 V was measured on a DLC-coated sample with the highest aspect ratio. No degradation of the emission current was observed in the plateau regime during a measurement period of 6 h. Finally, no decreasing performance of the field emission properties was found due to changes in the geometry or destructions.}, language = {en} } @inproceedings{ŁawrowskiLangerSchreineretal., author = {Ławrowski, Robert Damian and Langer, Christoph and Schreiner, Rupert and Sellmair, J.}, title = {Nano Emitters on Silicon Pillar Structures generated by a Focused Electron Beam Induced Deposition}, series = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, publisher = {IEEE}, doi = {10.1109/IVNC.2018.8520059}, pages = {1-2}, abstract = {Nano emitters were deposited by focused electron beam induced deposition of Trimethyl-(methylcyclopentadienyl)platinum(IV) on top of silicon pillars. The nano emitters were exactly positioned in the center on the top of up to four pillars of a quadratic arranged array of sixteen pillars with a pitch of 50 μm. Integral field emission measurements were performed in a diode configuration with a 50 μm mica spacer in a vacuum chamber at pressures of about 10 -9 mbar. The Fowler-Nordheim plots show a linear behavior, like expected for an n-type silicon material and a metal needle. The I-V measurement of the most promising sample shows an integral emission current up to 2 μm at a voltage of 600 V (12 MV/m) and an onset voltage for a current of 1 nA of about 300 V.}, language = {en} } @inproceedings{ŁawrowskiLangerPrommesbergeretal., author = {Ławrowski, Robert Damian and Langer, Christoph and Prommesberger, Christian and Schreiner, Rupert}, title = {Light emitting diodes based on three-dimensional epitaxial grown crystalline GaN rods}, series = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, booktitle = {7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, M{\"u}nchen}, publisher = {VDE-Verlag}, address = {M{\"u}nchen}, isbn = {978-3-8007-4491-6}, pages = {131 -- 134}, language = {en} } @inproceedings{ŁawrowskiLangerPrommesbergeretal., author = {Ławrowski, Robert Damian and Langer, Christoph and Prommesberger, Christian and Schreiner, Rupert}, title = {Field emission from three-dimensional epitaxial grown GaN-microrods}, series = {29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada}, booktitle = {29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada}, publisher = {IEEE}, issn = {2380-6311}, doi = {10.1109/IVNC.2016.7551477}, pages = {87 -- 88}, abstract = {A novel three-dimensional epitaxial technique allows on patterned substrates the realization of gallium nitride pillars, also known as nano- and microrods. The typical dimensions of the microrods are in the range of one micron for the radius of the hexagonal footprint and about 10 μm in height. The microrods consist of a semiconductor heterostructure with an n GaN core, a n-GaN shell, a p GaN shell and an intermediate quantum well layer. The field emission properties were investigated in diode configuration by integral field emission measurements in a vacuum chamber at pressures around 10 -9 mbar. The spacer was mica with a thickness of 50 μm. A metallized fine-meshed nitride grid (or a metallized Si-grid) was used as anode. A current of about 1 μA at a voltage of 1250 V (1750 V) was measured. An onset field of about 12.5 MV/m (20 MV/m) and field enhancement factors in the range of 200 to 500 (150 to 300) were found. The investigation with the fine-meshed grid showed an expected pronounced saturation region.}, language = {en} } @inproceedings{PrommesbergerLangerSchreiner, author = {Prommesberger, Christian and Langer, Christoph and Schreiner, Rupert}, title = {Stable and low noise field emission from single p-type Si-tips}, series = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan}, publisher = {IEEE}, doi = {10.1109/IVNC.2018.8520018}, pages = {1-2}, abstract = {Single gated p-type Si-tips with two different tip radii were fabricated. An emission current of 2.40 μA was measured for the sharp-edged tip at a voltage of 170 V. In contrast, a stable and reproducible emission behavior was observed with an increased tip radius resulting in a pronounced saturation region between 90 V and 150 V, but merely an emission current of 0.55 μA at 150 V. More remarkable is the stable emission behavior with fluctuation of ± 4 \% during a measurement period of 30 minutes. The integral emission current in a homogeneous tip array (16 emitters) showed nearly the same I-V characteristics compared to the single tip and is therefore, most dominated by only a stable single tip in the array.}, language = {en} } @inproceedings{PrommesbergerLangerŁawrowskietal., author = {Prommesberger, Christian and Langer, Christoph and Ławrowski, Robert Damian and Schreiner, Rupert}, title = {Field emission from black silicon structures with integrated gate electrode}, series = {29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada}, booktitle = {29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada}, publisher = {IEEE}, issn = {2380-6311}, doi = {10.1109/IVNC.2016.7551532}, pages = {219 -- 220}, abstract = {Black silicon structures with integrated gate electrode were realized by using an improved fabrication process. An enhanced insulation layer was achieved by a combination of dry and wet oxidation, and a gold layer was evaporated as gate electrode. The black silicon structures were prepared with a RIE/ICP etching process at room temperature. Arrays of 16 and 100 apertures with buried p-doped black silicon whiskers have been fabricated. These structures have an emitter height of approximately 1.5 μm with tip radii between 5 nm and 30 nm. The whiskers are surrounded by the gate electrode in a distance of 1.5 μm. Integral field emission measurements yielded an onset voltage of 92 V for 16 apertures and 60 V for 100 apertures for an emission current of 1 nA. Maximum emission currents up to 0.2 μA were observed for the array with 100 apertures at a cathode voltage of 200 V. Stability measurements showed a current fluctuation of ± 21\% at a mean value of the emission current of 12 nA over a period of 30 minutes for 16 apertures with b-Si whiskers.}, language = {en} } @inproceedings{LangerPrommesbergerŁawrowskietal., author = {Langer, Christoph and Prommesberger, Christian and Ławrowski, Robert Damian and Schreiner, Rupert and Huang, Yifeng and She, Juncong}, title = {Gated p-Si field emission cathode applied in an ionization vacuum gauge}, series = {29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada}, booktitle = {29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada}, publisher = {IEEE}, issn = {2380-6311}, doi = {10.1109/IVNC.2016.7551500}, pages = {145 -- 146}, abstract = {A commercial Bayard-Alpert ionization vacuum gauge was equipped with a field emission electron source based on a cathode consisting of an array of 16 gated, p-doped, and DLC-coated Si-tips and characterized. An anode current of about 1.3 μA led to an ion current of 7 fA at 3×10 -7 mbar and 0.8 pA at 4×10 -5 mbar. Whereas at pressures higher than 4×10 -5 mbar the emission current of the electron source decreased, the ratio of ion and anode current remained linear. A nearly constant sensitivity of ~ 17 mbar -1 of the ionization vacuum gauge within the investigated pressure range was depicted.}, language = {en} } @inproceedings{PrommesbergerLangerŁawrowskietal., author = {Prommesberger, Christian and Langer, Christoph and Ławrowski, Robert Damian and Schreiner, Rupert}, title = {Benzocyclobutene as a novel integrated spacer material in a field emission electron source}, series = {International Vacuum Nanoelectronics Conference (IVNC), 30th, 2017, Regensburg}, booktitle = {International Vacuum Nanoelectronics Conference (IVNC), 30th, 2017, Regensburg}, publisher = {IEEE}, doi = {10.1109/IVNC.2017.8051605}, pages = {192 -- 193}, abstract = {For the realization of a miniaturized field emission electron source we tested benzocyclobutene (BCB) as a new spacer material between cathode and anode. We fabricated black silicon emitters and characterized the emission behavior with an integrated 5 μm thin and large-area spacer of BCB. The integrated BCB layer allows the realization of a compact electron source with only two components consisting of a cathode with BCB and a grid. The comparison with other spacer materials like polyimide (25 μm thickness) or mica (50 μm thickness) revealed for the cathode with BCB a significantly reduced operational voltage of 240 V for a field emission current of 1 μA.}, language = {en} } @inproceedings{ŁawrowskiLangerPrommesbergeretal., author = {Ławrowski, Robert Damian and Langer, Christoph and Prommesberger, Christian and Dams, Florian and Serbun, Pavel and M{\"u}ller, G{\"u}nter and Schreiner, Rupert}, title = {Spitzen- und Kantenemitter aus Silizium mit einem hohen Aspektverh{\"a}ltnis f{\"u}r Ionisationsgassensoren}, series = {Mikrosystemtechnik als Schl{\"u}sseltechnologie der Systemintegration : 4. Landshuter Symposium Mikrosystemtechnik ; Tagungsband zum Symposium ; 12./13. M{\"a}rz 2014, Hochschule Landshut}, booktitle = {Mikrosystemtechnik als Schl{\"u}sseltechnologie der Systemintegration : 4. Landshuter Symposium Mikrosystemtechnik ; Tagungsband zum Symposium ; 12./13. M{\"a}rz 2014, Hochschule Landshut}, publisher = {Cluster Mikrosystemtechnik}, address = {Landshut}, isbn = {978-3-9812696-5-9}, pages = {28 -- 35}, abstract = {Durch die Optimierung von reaktivem Ionen{\"a}tzen mit induktiv gekoppeltem Plasma ist die Herstellung von verschiedenen Siliziumkathoden mit hoher Anisotropie und hohem Aspektverh{\"a}ltnis f{\"u}r Feldemissionsanwendungen m{\"o}glich. Simulationen mit COMSOL Multiphysics untermauern das Potential von solchen Spitzen- und Kantenfeldemittern. Die Ergebnisse der Simulation zeigen einen zwei- bis sechsfach h{\"o}heren Feld{\"u}berh{\"o}hungsfaktor der tiefge{\"a}tzten Strukturen im Vergleich zu identischen Emittern ohne zus{\"a}tzliche Tiefen{\"a}tzung. Feldemissionsmessungen best{\"a}tigen die Simulationsergebnisse. Der modifizierte Herstellungsprozess der Feldemitter erm{\"o}glicht somit einen zuverl{\"a}ssigen Betrieb von Feldemissionselektronenquellen bei kleineren makroskopischen Feldst{\"a}rken. Außerdem weisen die Messungen des Emissionsstroms im S{\"a}ttigungsbereich eine weitgehende Unabh{\"a}ngigkeit vom elektrischen Feld auf. Lokale Feldemissionsmessungen ergeben dadurch eine deutliche Stromstabilisierung, welche {\"u}ber große Feldst{\"a}rkenbereiche konstant bleibt. Die Nutzung der HAR-Emitter (high aspect ratio) ist damit eine gute Voraussetzung f{\"u}r einen zuverl{\"a}ssigen Betrieb der Emissionskathoden bei kleinen Feldst{\"a}rken f{\"u}r die Anwendung in Ionisationsgassensoren.}, language = {de} } @inproceedings{SchreinerLangerPrommesbergeretal., author = {Schreiner, Rupert and Langer, Christoph and Prommesberger, Christian and Ławrowski, Robert Damian and Dams, Florian and Bachmann, Michael and D{\"u}sberg, F. and Hofmann, M. and Pahlke, A. and Serbun, Pavel and Mingels, S. and M{\"u}ller, G{\"u}nter}, title = {Semiconductor field emission electron sources using a modular system concept for application in sensors and x-ray-sources}, series = {2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China}, booktitle = {2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China}, publisher = {IEEE}, doi = {10.1109/IVNC.2015.7225572}, pages = {178 -- 179}, abstract = {Semiconductor field emitters are suitable candidates for applications, which require a very stable field emission (FE) current and a high emission uniformity over the entire emission area. By using different materials and geometries, we are able to vary the FE characteristics within a wide range. Each specific application requires its own optimized design for the cathode as well as for the other parts of the FE electron source. To meet as many of these requirements as possible while using only a limited number of different prefabricated components, we established a modular system concept for our FE electron source. This allows the implementation of almost every cathode material. For first characterizations, we used gated p-type Si cathodes with 16 tips. We obtained stable FE currents of 0.4 μA for a grid-potential of 400 V and a gate potential of 100 V. Almost 100\% of the electrons are emitted towards the grid-electrode. Parasitic leakage paths, as well as the electron emission towards the gate-electrode can be neglected. Approximately 10\% of the electrons are transmitted through the grid and reach the external anode. This is in good agreement with the optical transmission through the grid-mesh.}, language = {en} } @inproceedings{BachmannDamsDuesbergetal., author = {Bachmann, Michael and Dams, Florian and D{\"u}sberg, F. and Hofmann, M. and Pahlke, A. and Langer, Christoph and Ławrowski, Robert Damian and Prommesberger, Christian and Schreiner, Rupert}, title = {Stability investigation of high aspect ratio n-type silicon field emitter arrays}, series = {2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China}, booktitle = {2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China}, publisher = {IEEE}, doi = {10.1109/IVNC.2015.7225584}, pages = {204 -- 205}, abstract = {Electron sources based on silicon field emitter arrays, produced in processes based on semiconductor technology, are good candidates for a miniaturized X-ray source. A key parameter for this application is the stability of the X-ray photon flux and, thus, the emission current. In the present work we have investigated the influence of the residual gas pressure and a resistor in series on the emission stability of a high aspect ratio n-type silicon emitter array with hybrid extraction electrode. An increase of current fluctuations was found for pressures above 10-6 mbar. High resistances in series to the emitter array alter the emission characteristics, but greatly suppress spikes in the emission current and improve its stability. This, however, strongly depends on the bias point. The field enhancement factor is not affected by the resistance. In a long term measurement the emission current was found to be constant after an initial phase of degradation.}, language = {en} } @inproceedings{LangerPrommesbergerDamsetal., author = {Langer, Christoph and Prommesberger, Christian and Dams, Florian and Serbun, Pavel and Bornmann, Benjamin and Mingels, Stephan and M{\"u}ller, G{\"u}ntner and Schreiner, Rupert}, title = {Si-Feldemissionskathoden f{\"u}r Anwendungen in miniaturisierten Ionisationsvakuumsensoren}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft e.V. (DPG), Regensburg, 10. - 15. M{\"a}rz 2013}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft e.V. (DPG), Regensburg, 10. - 15. M{\"a}rz 2013}, publisher = {Deutsche Physikalische Gesellschaft e.V.}, abstract = {Feldemissionselektronenquellen sind aufgrund ihrer prinzipiellen Vorteile gegen{\"u}ber Gl{\"u}hkathoden bereits seit l{\"a}ngerer Zeit Gegenstand der Forschung und werden bisher nur in einigen Spezialanwendungen erfolgreich eingesetzt. Hierbei werden Einzelspitzen mit Spannungen im kV-Bereich und Str{\"o}men im nA-Bereich betrieben. Dagegen werden f{\"u}r miniaturisierte Sensorsysteme eher Spannungen von ca. 100 V und Str{\"o}me von ca. 1 mA ben{\"o}tigt. Dazu wurden bisher meist Feldemissionskathoden mit CNTs vorgeschlagen, welche f{\"u}r Anwendungen in der Halbleiterindustrie aufgrund des Kohlenstoffanteils nicht erw{\"u}nscht sind. Ziel unserer Arbeit ist es, Si-basierte Elektronenquellen zu realisieren, die mit anderen miniaturisierten Vakuumsensoren auf einem Chip integrierbar sind. Mithilfe eines optimierten Herstellungsprozesses konnten wir p-Si-Spitzenarrays mit Spitzenradien von wenigen nm realisieren [1]. Messungen an diesen Strukturen zeigen ein sehr homogenes Emissionsverhalten, das vor allem im S{\"a}ttigungsbereich bei Emissionsstr{\"o}men von ca. 10 nA pro Spitze zeitlich stabil (Schwankungen < 5 \%) und optisch schaltbar (Faktor > 2.5) ist [2].}, language = {de} } @article{BiekerRoustaieSchlaaketal., author = {Bieker, Johannes and Roustaie, Farough and Schlaak, Helmut F. and Langer, Christoph and Schreiner, Rupert and Lotz, Marcel and Wilfert, Stefan}, title = {Field emission characterization of in situ deposited gold nanocones with variable cone densities}, series = {Journal of Vacuum Science and Technology B}, volume = {36}, journal = {Journal of Vacuum Science and Technology B}, number = {2}, publisher = {AIP Publishing}, doi = {10.1116/1.5009504}, abstract = {For the fabrication of field emitter cathodes with metallic nanocones, an in situ fabrication technique based on electrodeposition in an ion track etched polymer template was used. Three samples with nanocones made of gold and different cone densities were deposited on a circular electrode with a diameter of 2.5 mm, using templates with pore density of 6 × 104, 4 × 105, and 1 × 106 cones/cm2. The cones had a height of 24 μm, a base diameter between 3 and 3.75 μm, and a tip diameter below 500 nm. Integral field emission measurements revealed onset fields of down to 3.1 V/μm and average field enhancement factors of up to 1240. For one sample, the maximum emission current from the cathode reached 142.2 μA at an applied voltage of 338 V between cathode and extraction grid, which had a distance of 50 μm. To investigate the stability of the field emission current, cumulative long-term measurements were performed for over 50 h. A stable emission current of (31.0 ± 1.3) μA at an average applied voltage of 290 V (E = 5.8 V/μm) was observed. For currents above 100 μA, a decrease of the current and therefore a degradation of the emitter structures occurred.}, language = {en} } @inproceedings{PrommesbergerLangerŁawrowskietal., author = {Prommesberger, Christian and Langer, Christoph and Ławrowski, Robert Damian and Dams, Florian and Schreiner, Rupert and Ławrowski, Robert Damian}, title = {Gated p-Si field emitter arrays for sensor applications}, series = {2015 28th International Vacuum Nanoelectronics Conference (IVNC)}, booktitle = {2015 28th International Vacuum Nanoelectronics Conference (IVNC)}, publisher = {IEEE}, doi = {10.1109/IVNC.2015.7225567}, pages = {164 -- 165}, abstract = {We report on gated p-type Si-tip array cathodes for implementation into field emission electron sources for sensor applications. Arrays of 16 and 100 tips with tip heights of 3 μm and tip radii below 30 nm with integrated gate electrodes concentrically positioned 2 μm below the tip apexes were fabricated using an improved process, which leads to an enhanced isolation layer quality with sufficient breakdown field strengths and low leakage currents. Integral measurements with a fixed grid potential of 400 V showed emission currents up to 35 μA for 100 tips at a cathode voltage of 150 V and an almost negligible parasitic gate current. The array with 16 p-type Si-tips showed a significant stabilization of the emission current in the range of 0.3 - 0.4 μA, for cathode voltages between 90 V and 150 V. The current fluctuation in this saturation regime was measured for 10 minutes and a value of less than ± 1\% was observed. No degradation of the cathode was found after 6 hours of operation at a constant cathode voltage of 100 V and a constant grid voltage of 400 V.}, language = {en} } @inproceedings{KnappLangerPrommesbergeretal., author = {Knapp, Wolfram and Langer, Christoph and Prommesberger, Christian and Lindner, Matthias and Schreiner, Rupert}, title = {Investigations of the transition from field electron emission to stable plasma discharge in a micro electron source at vacuum pressure}, series = {2017 30th International Vacuum Nanoelectronics Conference (IVNC), 10-14 July 2017, Regensburg, Germany}, booktitle = {2017 30th International Vacuum Nanoelectronics Conference (IVNC), 10-14 July 2017, Regensburg, Germany}, publisher = {IEEE}, doi = {10.1109/IVNC.2017.8051594}, pages = {166 -- 167}, abstract = {We report on the transition from field electron emission to plasma discharges. During an experiment with a miniaturized field emission electron source a plasma discharge accompanied by a luminous effect was observed. A novel graphical evaluation method was used to interpret and to compare the observed phenomenon.}, language = {en} } @incollection{ŁawrowskiPrommesbergerLangeretal., author = {Ławrowski, Robert Damian and Prommesberger, Christian and Langer, Christoph and Dams, Florian and Schreiner, Rupert}, title = {Feldemissionselektronenquellen basierend auf Siliziumemittern mit hohen Aspektverh{\"a}ltnis}, series = {Forschungsbericht der OTH Regensburg 2013}, booktitle = {Forschungsbericht der OTH Regensburg 2013}, address = {Regensburg}, pages = {47 -- 48}, language = {de} } @inproceedings{PrommesbergerDamsLangeretal., author = {Prommesberger, Christian and Dams, Florian and Langer, Christoph and Schreiner, Rupert and Rutkowski, S. and Bornmann, Benjamin and M{\"u}ller, G{\"u}ntner}, title = {Simulation of electron trajectories of a field emission electron source in triode configuration by using finite element methods}, series = {24th International Vacuum Nanoelectronics Conference (IVNC), 2011 : 18 - 22 July 2011, Historische Stadthalle Wuppertal, Germany}, booktitle = {24th International Vacuum Nanoelectronics Conference (IVNC), 2011 : 18 - 22 July 2011, Historische Stadthalle Wuppertal, Germany}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-3-00-035081-8}, issn = {2380-6311}, pages = {144 -- 145}, abstract = {The finite element simulation program COMSOL Multiphysics® was used to simulate the emission efficiency of a silicon tip electron source in triode configuration for different geometries and electrode potentials. The simulation predicts a maximum emission efficiency of 84\% for an optimized structure. In a second simulation a gate electrode was concentrically arranged above a single CNT column. Here, the efficiency was simulated as a function of gate hole geometry, electrode potentials and distances between the electrodes. The simulation shows that a conical shape of the gate hole results in an efficiency up to nearly 100\%.}, language = {en} } @article{LangerPrommesbergerŁawrowskietal., author = {Langer, Christoph and Prommesberger, Christian and Ławrowski, Robert Damian and Schreiner, Rupert and Serbun, Pavel and M{\"u}ller, G{\"u}nter and D{\"u}sberg, Felix and Hofmann, Martin and Bachmann, Michael and Pahlke, Andreas}, title = {Field emission properties of p-type black silicon on pillar structures}, series = {Journal of Vacuum Science \& Technology B}, volume = {34}, journal = {Journal of Vacuum Science \& Technology B}, number = {2}, doi = {10.1116/1.4943919}, abstract = {Arrays of black silicon field emission pillar structures were fabricated on p-type silicon substrates. Two types of samples with the same number of pillars (arrays of 10 × 10) but different pillar heights (8 and 20 μm) were prepared as well as a black silicon reference sample without pillars. The field emission properties of these cathodes were investigated both by means of integral current-voltage measurements and by field emission scanning microscopy. Samples with a pillar height of 20 μm revealed onset fields as low as 6.4 V/μm, field enhancement factors up to 800, and emission currents up to 8 μA at an applied field of 20 V/μm. Due to the p-type material, a saturation of the emission current for fields above 11 V/μm was observed. This saturation leads to a stable operation with a current fluctuation of less than ±8\%. It was found that samples with a pillar height of 20 μm showed improved emission characteristics compared to samples with a pillar height of 8 μm or without pillars. The voltage maps revealed an increased emission homogeneity after a "burn-in" sequence of the sample. The current map showed that a few of the pillars dominate the emission. Integral current stability measurements were performed under different vacuum pressures, in order to investigate altered emission behavior and a potential degradation of the emitters. At pressures above 10-6 mbar, the sample starts to degrade irreversibly. Nevertheless, even after a harsh treatment over 30 min at 5 × 10-5 mbar and at an applied field of 23 V/μm, the cathode was still operating, and did not fail during further operation over 20 h at 5 × 10-8 mbar and at an applied field of 28 V/μm.}, language = {en} } @article{SchreinerLangerPrommesbergeretal., author = {Schreiner, Rupert and Langer, Christoph and Prommesberger, Christian and Dams, Florian}, title = {Compact and Energy-Efficient Field Emission Cathodes for Sensor Applications}, series = {Advanced Materials Research}, volume = {1024}, journal = {Advanced Materials Research}, publisher = {Scientific.net}, doi = {10.4028/www.scientific.net/amr.1024.372}, pages = {372 -- 375}, abstract = {We report on miniaturized silicon field emitter arrays for the application in compact and energy-saving vacuum-microelectronic devices, e.g. sensors or x-ray tubes. Since standard silicon semiconductor technology has been used for the fabrication, they may be easily integrated with other silicon based circuits and devices on the same chip. The silicon tip geometry and the operating conditions were optimized in order to obtain highly uniform and stable electron field emission from large area cathode arrays. A series of uniform hexagonal tip arrays containing each 547 tips were fabricated and characterized. The electron emission properties of both individual tips as well as of complete emitter arrays were investigated. A saturation level in the voltage-current characteristics was found, which can be explained by the limitation of the supply of electrons due to the p-type silicon wafer material. When operating the arrays in the current saturation regime at an emission current of ~ 1 nA per tip, a highly stable and low noise emission can be observed.}, language = {en} } @misc{ScharfenbergMottokArtmannetal., author = {Scharfenberg, Georg and Mottok, J{\"u}rgen and Artmann, Christina and Hobelsberger, Martin and Paric, Ivan and Großmann, Benjamin and Pohlt, Clemens and Wackerbarth, Alena and Pausch, Uli and Heidrich, Christiane and Fadanelli, Martin and Elsner, Michael and P{\"o}cher, Daniel and Pittroff, Lenz and Beer, Stefan and Br{\"u}ckl, Oliver and Haslbeck, Matthias and Sterner, Michael and Thema, Martin and Muggenthaler, Nicole and Lenck, Thorsten and G{\"o}tz, Philipp and Eckert, Fabian and Deubzer, Michael and Stingl, Armin and Simsek, Erol and Kr{\"a}mer, Stefan and Großmann, Benjamin and Schlegl, Thomas and Niedersteiner, Sascha and Berlehner, Thomas and Joblin, Mitchell and Mauerer, Wolfgang and Apel, Sven and Siegmund, Janet and Riehle, Dirk and Weber, Joachim and Palm, Christoph and Zobel, Martin and Al-Falouji, Ghassan and Prestel, Dietmar and Scharfenberg, Georg and Mandl, Roland and Deinzer, Arnulf and Halang, W. and Margraf-Stiksrud, Jutta and Sick, Bernhard and Deinzer, Renate and Scherzinger, Stefanie and Klettke, Meike and St{\"o}rl, Uta and Wiech, Katharina and Kubata, Christoph and Sindersberger, Dirk and Monkman, Gareth J. and Dollinger, Markus and Dembianny, Sven and K{\"o}lbl, Andreas and Welker, Franz and Meier, Matthias and Thumann, Philipp and Swidergal, Krzysztof and Wagner, Marcus and Haug, Sonja and Vernim, Matthias and Seidenst{\"u}cker, Barbara and Weber, Karsten and Arsan, Christian and Schone, Reinhold and M{\"u}nder, Johannes and Schroll-Decker, Irmgard and Dillinger, Andrea Elisabeth and Fuchshofer, Rudolf and Monkman, Gareth J. and Shamonin (Chamonine), Mikhail and Geith, Markus A. and Koch, Fabian and {\"U}hlin, Christian and Schratzenstaller, Thomas and Saßmannshausen, Sean Patrick and Auchter, Eberhard and Kriz, Willy and Springer, Othmar and Thumann, Maria and Kusterle, Wolfgang and Obermeier, Andreas and Udalzow, Anton and Schmailzl, Anton and Hierl, Stefan and Langer, Christoph and Schreiner, Rupert}, title = {Forschungsbericht / Ostbayerische Technische Hochschule Regensburg}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-00-048589-3}, doi = {10.35096/othr/pub-1386}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-13867}, language = {de} } @misc{BeimlerLeisslEbneretal., author = {Beimler, Josef and Leißl, Caroline and Ebner, Lena and Elsner, Michael and M{\"u}hlbauer, Gerhard and Kohlert, Dieter and Schubert, Martin J. W. and Weiß, Andreas P. and Sterner, Michael and Raith, Thomas and Afranseder, Martin and Krapf, Tobias and Mottok, J{\"u}rgen and Siemers, Christian and Großmann, Benjamin and H{\"o}cherl, Johannes and Schlegl, Thomas and Schneider, Ralph and Milaev, Johannes and Rampelt, Christina and Roduner, Christian and Glowa, Christoph and Bachl, Christoph and Schliekmann, Claus and Gnan, Alfons and Grill, Martin and Ruhland, Karl and Piehler, Thomas and Friers, Daniel and Wels, Harald and Pflug, Kenny and Kucera, Markus and Waas, Thomas and Schlachetzki, Felix and Boy, Sandra and Pemmerl, Josef and Leis, Alexander and Welsch, Andreas F.X. and Graf, Franz and Zenger, Gerhard and Volbert, Klaus and Waas, Thomas and Scherzinger, Stefanie and Klettke, Meike and St{\"o}rl, Uta and Heyl, C. and Boldenko, A. and Monkman, Gareth J. and Kujat, Richard and Briem, Ulrich and Hierl, Stefan and Talbot, Sebastian and Schmailzl, Anton and Ławrowski, Robert Damian and Prommesberger, Christian and Langer, Christoph and Dams, Florian and Schreiner, Rupert and Valentino, Piergiorgio and Romano, Marco and Ehrlich, Ingo and Furgiuele, Franco and Gebbeken, Norbert and Eisenried, Michael and Jungbauer, Bastian and Hutterer, Albert and Bauhuber, Michael and Mikrievskij, Andreas and Argauer, Monika and Hummel, Helmut and Lechner, Alfred and Liebetruth, Thomas and Schumm, Michael and Joseph, Saskia and Reschke, Michael and Soska, Alexander and Schroll-Decker, Irmgard and Putzer, Michael and Rasmussen, John and Dendorfer, Sebastian and Weber, Tim and Al-Munajjed, Amir Andreas and Verkerke, Gijsbertus Jacob and Renkawitz, Tobias and Haug, Sonja and Rudolph, Clarissa and Zeitler, Annika and Schaubeck, Simon and Steffens, Oliver and Rechenauer, Christian and Schulz-Brize, Thekla and Fleischmann, Florian and Kusterle, Wolfgang and Beer, Anne and Wagner, Bernd and Neidhart, Thomas}, title = {Forschungsbericht 2013}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, doi = {10.35096/othr/pub-799}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-7990}, pages = {80}, language = {de} } @misc{MauererRexhepajMonkmanetal., author = {Mauerer, Wolfgang and Rexhepaj, Tanja and Monkman, Gareth J. and Sindersberger, Dirk and Diermeier, Andreas and Neidhart, Thomas and Wolfrum, Dominik and Sterner, Michael and Heberl, Michael and Nusko, Robert and Maier, Georg and Nagl, Klaus and Reuter, Monika and Hofrichter, Andreas and Lex, Thomas and Lesch, Florian and Kieninger, B{\"a}rbel and Szalo, Alexander Eduard and Zehner, Alexander and Palm, Christoph and Joblin, Mitchell and Apel, Sven and Ramsauer, Ralf and Lohmann, Daniel and Westner, Markus and Strasser, Artur and Munndi, Maximilian and Ebner, Lena and Elsner, Michael and Weiß, Nils and Segerer, Matthias and Hackenberg, Rudolf and Steger, Sebastian and Schmailzl, Anton and Dostalek, Michael and Armbruster, Dominik and Koch, Fabian and Hierl, Stefan and Thumann, Philipp and Swidergal, Krzysztof and Wagner, Marcus and Briem, Ulrich and Diermeier, Andreas and Spreitzer, Stefan and Beiderbeck, Sabrina and Hook, Christian and Zobel, Martin and Weber, Tim and Groß, Simon and Penzkofer, Rainer and Dendorfer, Sebastian and Schillitz, Ingo and Bauer, Thomas and Rudolph, Clarissa and Schmidt, Katja and Liebetruth, Thomas and Hamer, Markus and Haug, Sonja and Vernim, Matthias and Weber, Karsten and Saßmannshausen, Sean Patrick and Books, Sebastian and Neuleitner, Nikolaus and Rechenauer, Christian and Steffens, Oliver and Kusterle, Wolfgang and G{\"o}mmel, Roland and Wellnitz, Felix and Stierstorfer, Johannes and Stadler, Dominik and Hofmann, Matthias J. and Motschmann, Hubert and Shamonin (Chamonine), Mikhail and Bleicher, Veronika and Fischer, Sebastian and Hackenberg, Rudolf and Horn, Anton and Kawasch, Raphael and Petzenhauser, Michael and Probst, Tobias and Udalzow, Anton and Dams, Florian and Schreiner, Rupert and Langer, Christoph and Prommesberger, Christian and Ławrowski, Robert Damian}, title = {Forschungsbericht 2016}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, doi = {10.35096/othr/pub-1384}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-13840}, language = {de} } @misc{WeberDendorferSuessetal., author = {Weber, Karsten and Dendorfer, Sebastian and S{\"u}ß, Franz and Kubowitsch, Simone and Schratzenstaller, Thomas and Haug, Sonja and Mohr, Christa and Kiesl, Hans and Drechsler, J{\"o}rg and Westner, Markus and Kobus, J{\"o}rn and Schubert, Martin J. W. and Zenger, Stefan and Pietsch, Alexander and Weiß, Josef and Hinterseer, Sebastian and Schieck, Roland and Scherzinger, Stefanie and Klettke, Meike and Ringlstetter, Andreas and St{\"o}rl, Uta and Bissyand{\´e}, Tegawend{\´e} F. and Seeburger, Achim and Schindler, Timo and Ramsauer, Ralf and Kiszka, Jan and K{\"o}lbl, Andreas and Lohmann, Daniel and Mauerer, Wolfgang and Maier, Johannes and Scorna, Ulrike and Palm, Christoph and Soska, Alexander and Mottok, J{\"u}rgen and Ellermeier, Andreas and V{\"o}gele, Daniel and Hierl, Stefan and Briem, Ulrich and Buschmann, Knut and Ehrlich, Ingo and Pongratz, Christian and Pielmeier, Benjamin and Tyroller, Quirin and Monkman, Gareth J. and Gut, Franz and Roth, Carina and Hausler, Peter and Bierl, Rudolf and Prommesberger, Christian and Ławrowski, Robert Damian and Langer, Christoph and Schreiner, Rupert and Huang, Yifeng and She, Juncong and Ottl, Andreas and Rieger, Walter and Kraml, Agnes and Poxleitner, Thomas and Hofer, Simon and Heisterkamp, Benjamin and Lerch, Maximilian and Sammer, Nike and Golde, Olivia and Wellnitz, Felix and Schmid, Sandra and Muntschick, Claudia and Kusterle, Wolfgang and Paric, Ivan and Br{\"u}ckl, Oliver and Haslbeck, Matthias and Schmidt, Ottfried and Schwanzer, Peter and Rabl, Hans-Peter and Sterner, Michael and Bauer, Franz and Steinmann, Sven and Eckert, Fabian and Hofrichter, Andreas}, title = {Forschungsbericht 2017}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-9818209-3-5}, doi = {10.35096/othr/pub-1383}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-13835}, subject = {Forschung}, language = {de} } @misc{LautenschlaegerLeisDendorferetal., author = {Lautenschl{\"a}ger, Toni and Leis, Alexander and Dendorfer, Sebastian and Palm, Christoph and Schreiner, Rupert and Langer, Christoph and Prommesberger, Christian and Ławrowski, Robert Damian and Dams, Florian and Bornmann, Benjamin and Navitski, Aliaksandr and Serbun, Pavel and M{\"u}ller, G{\"u}nter and Liebetruth, Thomas and Kohlert, Dieter and Pernsteiner, Jochen and Schreier, Franz and Heerklotz, Sabrina and Heerklotz, Allwin and Boos, Alexander and Herwald, Dominik and Monkman, Gareth J. and Treiber, Daniel and Mayer, Matthias and H{\"o}rner, Eva and Bentz, Alexander and Shamonin (Chamonine), Mikhail and Johansen, S{\o}ren Peter and Reichel, Marco and Stoll, Andrea and Briem, Ulrich and Dullien, Silvia and Renkawitz, Tobias and Weber, Tim and Dendorfer, Sebastian and Grifka, Joachim and Penzkofer, Rainer and Barnsteiner, K. and Jovanovik, M. and Wernecke, P. and V{\"o}gele, A. and Bachmann, T. and Pl{\"o}tz, Martin and Schliekmann, Claus and Wels, Harald and Helmberger, Paul and Kaspar, M. and H{\"o}nicka, M. and Schrammel, Siegfried and Enser, Markus and Schmidmeier, Monika and Schroll-Decker, Irmgard and Haug, Sonja and Gelfert, Verena and Vernim, Matthias}, title = {Forschungsbericht 2012}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, doi = {10.35096/othr/pub-783}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-7834}, pages = {64}, language = {de} } @article{BerndtMuggliWittweretal., author = {Berndt, Dominik and Muggli, Josef and Wittwer, Franz and Langer, Christoph and Heinrich, Stephan and Knittel, Thorsten and Schreiner, Rupert}, title = {MEMS-based thermal conductivity sensor for hydrogen gas detection in automotive applications}, series = {Sensors and Actuators A: Physical}, volume = {305}, journal = {Sensors and Actuators A: Physical}, number = {April}, publisher = {Elsevier}, doi = {10.1016/j.sna.2019.111670}, abstract = {Accurate detection of hydrogen gas in vehicle interiors is very important for the future of a fuel cell car. Since this type of gas is highly volatile and flammable, the measurement methods have to be very reliable and precise due to safety reasons. In this paper a thermal conductivity sensor for hydrogen gas detection is presented, exhibiting a lower detection limit of 2000 ppm hydrogen in laboratory air. The sensor element is realized by micro-fabrication techniques on silicon wafers. The heated filament is exposed by a selective wet etching process creating a micro-hotplate on a thin membrane. In order to minimize power consumption, the sensor is operated in pulsed mode. Hydrogen gas detection was carried out using a synthetic gas testbench. Measurements of hydrogen contents ranging from 0\% to 4\% with an increment of 0.5\% were successfully performed for ambient gas temperatures between -15°C and 84°C. Including humidity, high moisture contents have the greatest influence on thermal conductivity. This was predicted in theoretical investigations and confirmed in experiments. For evaluation, both the change in resistance ΔR as well as the time constant τ were taken as sensor output. For both quantities, the previously established theoretical relationship with thermal conductivity could be confirmed.}, language = {en} } @inproceedings{LindnerBerndtPrommesbergeretal., author = {Lindner, Matthias and Berndt, Dominik and Prommesberger, Christian and Langer, Christoph and Schreiner, Rupert}, title = {Field emission assisted micro plasma discharges at vacuum and atmospheric pressures}, series = {31st International Vacuum Nanoelectronics Conference (IVNC), 2018, Kyoto, Japan}, booktitle = {31st International Vacuum Nanoelectronics Conference (IVNC), 2018, Kyoto, Japan}, doi = {10.1109/IVNC.2018.8520181}, pages = {2}, abstract = {Spatially confined non-equilibrium plasmas at vacuum and atmospheric pressure in the dimensions from a few microns to one millimeter are a promising approach to the generation and maintenance of stable glow discharges. The realization of these micro-discharges or micro-plasmas enable more accurate investigations in the field of micro plasma research. We report on field emission assisted micro plasmas excited by an alternating current with frequencies up to 1 kHz. Due to the field enhancement caused by an array of Si nano-tip structures the ignition voltage of stable plasma discharges can be reduced by 30\%.}, language = {en} } @inproceedings{BerndtLindnerTschurtschenthaleretal., author = {Berndt, Dominik and Lindner, Matthias and Tschurtschenthaler, Karl and Langer, Christoph and Schreiner, Rupert}, title = {Miniaturized Plasma Actuator Flow Measurements by MEMS-Based Thermal Conductivity Sensors}, series = {MDPI Proceedings of Eurosensors 2018, 9-12 September, Graz}, volume = {Vol.13}, booktitle = {MDPI Proceedings of Eurosensors 2018, 9-12 September, Graz}, number = {2}, doi = {10.3390/proceedings2130939}, abstract = {The gasflow created by a minaturized dielectric barrier discharge (DBD) plasma actuator is measured by a MEMS-based thermal conductivity gas sensor giving an indication of flow velocity and flow direction. The possiblity of several sensors in a small area gives a far better accuracy of local flow phenomena compared to conventional sensors. This is important for a better understanding of plasma- induced flow characteristics.}, language = {en} } @article{LangerBerndtSchreiner, author = {Langer, Christoph and Berndt, Dominik and Schreiner, Rupert}, title = {Sensitivity of thermal conductivity vacuum gauges for constant current and constant temperature operation}, series = {Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics}, volume = {40}, journal = {Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics}, number = {5}, publisher = {AIP Publishing}, doi = {10.1116/6.0001964}, abstract = {To optimize the measurement range of thermal conductivity vacuum gauges, an expression for the sensitivity is required that takes into account all geometrical, material-specific, and operating parameters. Therefore, equations of the sensor output signal as a function of the pressure for the constant current and the constant temperature mode have been developed analytically. Based on these equations, the sensitivity of the vacuum gauge and its influencing parameters was investigated and discussed. For comparable conditions, the constant temperature operation shows a significantly higher sensitivity for high pressures, while the constant current operation shows higher sensitivity at low pressures. The sensitivity in both the constant current and the constant temperature mode depends on the ratio of the filament surface area and the parasitic thermal conductance. In addition, for the constant current operation, the sensitivity also depends on the current value and the temperature coefficient of the filament resistor. For the constant temperature operation, the sensitivity additionally depends on the distance of the filament and the reference plane. However, to extend the measurement range of a thermal conductivity vacuum gauge toward low pressures, a reduction of the parasitic thermal conductance is mandatory for both the constant current and the constant temperature mode.}, language = {en} } @misc{AppelhansKampmannMottoketal., author = {Appelhans, Marie-Luise and Kampmann, Matthias and Mottok, J{\"u}rgen and Riederer, Michael and Nagl, Klaus and Steffens, Oliver and D{\"u}nnweber, Jan and Wildgruber, Markus and Roth, Julius and Stadler, Timo and Palm, Christoph and Weiß, Martin Georg and Rochholz, Sandra and Bierl, Rudolf and Gschossmann, Andreas and Haug, Sonja and Schmidbauer, Simon and Koch, Anna and Westner, Markus and Bary, Benedikt von and Ellermeier, Andreas and V{\"o}gele, Daniel and Maiwald, Frederik and Hierl, Stefan and Schlamp, Matthias and Ehrlich, Ingo and Siegl, Marco and H{\"u}ntelmann, Sven and Wildfeuer, Matthias and Br{\"u}ckl, Oliver and Sterner, Michael and Hofrichter, Andreas and Eckert, Fabian and Bauer, Franz and Dawoud, Belal and Rabl, Hans-Peter and Gamisch, Bernd and Schmidt, Ottfried and Heberl, Michael and Thema, Martin and Mayer, Ulrike and Eller, Johannes and Sippenauer, Thomas and Adelt, Christian and Haslbeck, Matthias and Vogl, Bettina and Mauerer, Wolfgang and Ramsauer, Ralf and Lohmann, Daniel and Sax, Irmengard and Gabor, Thomas and Feld, Sebastian and Linnhoff-Popien, Claudia and Ławrowski, Robert Damian and Langer, Christoph and Schreiner, Rupert and Sellmair, Josef}, title = {Forschung 2019}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-9818209-7-3}, doi = {10.35096/othr/pub-789}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-7890}, pages = {72}, abstract = {Bericht mit Forschungsprojekten aus verschiedenen Bereichen der OTH Regensburg mit dem Schwerpunktthema "K{\"u}nstliche Intelligenz" und einem Gespr{\"a}ch zur "Medizin der Zukunft"}, subject = {Forschung}, language = {de} } @inproceedings{SerbunPorshynMuelleretal., author = {Serbun, Pavel and Porshyn, V. and M{\"u}ller, G{\"u}nter and Mingels, S. and L{\"u}tzenkirchen-Hecht, Dirk and Bachmann, Michael and D{\"u}sberg, Felix and Dams, Florian and Hofmann, Martin and Pahlke, Andreas and Prommesberger, Christian and Langer, Christoph and Ławrowski, Robert Damian and Schreiner, Rupert}, title = {Field emission behavior of Au-tip-coated p-type Si pillar structures}, series = {29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada}, booktitle = {29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada}, publisher = {IEEE}, issn = {2380-6311}, doi = {10.1109/IVNC.2016.7551516}, pages = {181 -- 182}, abstract = {Precisely aligned high-aspect-ratio (HAR) silicon tip arrays were fabricated using enhanced reactive ion etching with an inductively-coupled-plasma followed by a sharpening oxidation. A gold thin film was then sputtered only on the tips of the HAR structures. Field-emission (FE) properties from Au-coated HAR p-Si tip array cathodes have been systematically investigated by means of field emission scanning microscopy (FESM). A rather high efficiency of the HAR Si structures (71\% at 550 V), but limited homogeneous FE with currents of 1-600 nA might be correlated with the varying geometry of the tips and the presence of oxides. I-V measurements of single Au-coated HAR emitters revealed activation effects and the saturation current region at 3 nA. An increase of the saturation current by 4 orders of magnitude was observed during 20 hours of conditioning at constant voltage, which finally resulted in nearly reproducible FN curves with a ß-factor of 473. An excellent stability of the emission current of less than 1 \% was obtained during the additional long-time conditioning at constant voltage. Optical switching under halogen lamp illumination resulted in at least 2 times higher saturation currents and showed a linear dependence of the FE current on the light color temperature.}, language = {en} } @misc{BroserFalterŁawrowskietal., author = {Broser, Christian and Falter, Thomas and Ławrowski, Robert Damian and Altenbuchner, Amelie and V{\"o}gele, Daniel and Koss, Claus and Schlampp, Matthias and Dunnweber, Jan and Steffens, Oliver and Heckner, Markus and Jaritz, Sabine and Schiegl, Thomas and Corsten, Sabine and Lauer, Norina and Guertler, Katherine and Koenig, Eric and Haug, Sonja and Huber, Dominik and Birkenmaier, Clemens and Krenkel, Lars and Wagner, Thomas and Justus, Xenia and Saßmannshausen, Sean Patrick and Kleine, Nadine and Weber, Karsten and Braun, Carina N. and Giacoppo, Giuliano and Heinrich, Michael and Just, Tobias and Schreck, Thomas and Schnabl, Andreas and Gilmore, Amador T{\´e}ran and Roeslin, Samuel and Schmid, Sandra and Wellnitz, Felix and Malz, Sebastian and Maurial, Andreas and Hauser, Florian and Mottok, J{\"u}rgen and Klettke, Meike and Scherzinger, Stefanie and St{\"o}rl, Uta and Heckner, Markus and Bazo, Alexander and Wolff, Christian and Kopper, Andreas and Westner, Markus and Pongratz, Christian and Ehrlich, Ingo and Briem, Ulrich and Hederer, Sebastian and Wagner, Marcus and Schillinger, Moritz and G{\"o}rlach, Julien and Hierl, Stefan and Siegl, Marco and Langer, Christoph and Hausladen, Matthias and Schreiner, Rupert and Haslbeck, Matthias and Kreuzer, Reinhard and Br{\"u}ckl, Oliver and Dawoud, Belal and Rabl, Hans-Peter and Gamisch, Bernd and Schmidt, Ottfried and Heberl, Michael and G{\"a}nsbauer, Bianca and Bick, Werner and Ellermeier, Andreas and Monkman, Gareth J. and Prem, Nina and Sindersberger, Dirk and Tschurtschenthaler, Karl and Aurbach, Maximilian and Dendorfer, Sebastian and Betz, Michael A. and Szecsey, Tamara and Mauerer, Wolfgang and Murr, Florian}, title = {Forschung 2018}, editor = {Baier, Wolfgang}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg}, isbn = {978-3-9818209-5-9}, doi = {10.35096/othr/pub-1382}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-13826}, pages = {98}, subject = {Forschung}, language = {de} }