@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} } @article{SchelsEdlerHerdletal., author = {Schels, Andreas and Edler, Simon and Herdl, Florian and Hansch, Walter and Bachmann, Michael and Ritter, Daniela and Dudeck, Markus and Duesberg, Felix and Meyer, Manuel and Pahlke, Andreas and Hausladen, Matthias and Buchner, Philipp and Schreiner, Rupert}, title = {In situ quantitative field emission imaging using a low-cost CMOS imaging sensor}, series = {Journal of Vacuum Science \& Technology B}, volume = {40}, journal = {Journal of Vacuum Science \& Technology B}, number = {1}, publisher = {AIP Publishing}, doi = {10.1116/6.0001551}, abstract = {Spatially resolved field emission measurements represent an important factor in further development of existing field emitter concepts. In this work, we present a novel approach that allows quantitative analysis of individual emission spots from integral current-voltage measurements using a low-cost and commercially available CMOS camera. By combining different exposure times to extrapolate oversaturated and underexposed pixels, a near congruence of integral current and image brightness is shown. The extrapolation also allows parallel investigation of all individual tips participating in the total current with currents ranging from a few nanoampere to one microampere per tip. The sensitivity, which is determined by the integral brightness-to-current ratio, remains unchanged within the measurement accuracy even after ten full measurement cycles. Using a point detection algorithm, the proportional current load of each individual tip of the field emitter array is analyzed and compared at different times during the initial measurement cycle. Together with the extracted I-V curves of single emission spots from the integral measurement, the results indicate the effect of premature burnout of particularly sharp tips during conditioning of the emitter.}, language = {en} } @article{EdlerSchelsHerdletal., author = {Edler, Simon and Schels, Andreas and Herdl, Florian and Hansch, Walter and Bachmann, Michael and Dudeck, Markus and Duesberg, Felix and Pahlke, Andreas and Hausladen, Matthias and Buchner Philipp, and Schreiner, Rupert}, title = {Origin of the current saturation level of p-doped silicon field emitters}, series = {Journal of Vacuum Science \& Technology B}, volume = {40}, journal = {Journal of Vacuum Science \& Technology B}, number = {1}, publisher = {AIP Publishing}, doi = {10.1116/6.0001554}, abstract = {Using p-type semiconductors for field emitters is one simple way to realize an integrated current limiter to improve the lifetime of the cathode. In this work, the origin of the current saturation of p-type silicon emitters is investigated in detail. Single emitters are electrically characterized and compared to simulation results. With a simulation model considering a high surface generation rate and elevated tip temperature, a good agreement to the measured data is found. This observation is supported further by alteration of the surface experimentally. Electrical measurements after different treatments in hydrofluoric acid as well as heated and subsequent operation at room temperature are well explained by the influence of surface generation. Furthermore, it is shown that the field penetration leads to a small voltage drop and a strong geometry-dependent reduction of the field enhancement factor.}, language = {en} } @inproceedings{TschurtschenthalerKrenkelSchreiner, author = {Tschurtschenthaler, Karl and Krenkel, Lars and Schreiner, Rupert}, title = {Mechano-optical micro pillar sensor for biofluidmechanic wall shear stress measurements}, series = {25th Congress of the European Society of Biomechanics (ESB), July 7-10, 2019, Vienna, Austria}, booktitle = {25th Congress of the European Society of Biomechanics (ESB), July 7-10, 2019, Vienna, Austria}, language = {en} } @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{DamsSchreiner, author = {Dams, Florian and Schreiner, Rupert}, title = {A high thermal resistance MEMS-based Pirani vacuum sensor chip}, series = {Smart sensors, actuators and MEMS VI : 24 - 26 April 2013, Grenoble, France / [part of SPIE microtechnologies]}, booktitle = {Smart sensors, actuators and MEMS VI : 24 - 26 April 2013, Grenoble, France / [part of SPIE microtechnologies]}, publisher = {SPIE}, address = {Bellingham, Wash.}, doi = {10.1117/12.2017345}, abstract = {The performance of thermal conductivity vacuum gauges can be improved by a well-designed geometry. The lower measurement range limit is determined by the size of the active sensing area and the thermal conduction heat losses through the supporting structures. The upper measurement range is limited by the distance between the heated element and the cold reference plane. Silicon based MEMS-technology gives the possibility to fabricate both sensing structures with suitable areas out of low thermal conductive materials and narrow gaps in order to extend the measurement range in both directions. In this work we present a MEMS-process to fabricate high thermal resistance sensor structures. The rectangular sensitive areas are anchored by four beams and are structured out of low thermal conductive PECVD-siliconnitride films with 1 µm in thickness. The metallic heating structure is completely embedded in the SiN-layer. Both sensitive area and its support beams were released from the silicon bulk material by anisotropic underetching. In this way a free-supporting structure with a gap of 150 μm to the silicon substrate was formed. The influence of the filament geometry and temperature was systematically investigated to determine the properties of the chips as thermal conductivity vacuum gauges. The temperature of the sensitive area was held constant by a self-balancing bridge circuit and the heating power was measured by a Δ-Σ-ADC. The average solid state thermal conductivity is in the order of 106WK1. The measuring range of the most sensitive structures covers 8 orders of magnitude from 105 mbar to 1000mbar.}, 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} } @inproceedings{BerndtLindnerSchreineretal., author = {Berndt, Dominik and Lindner, Matthias and Schreiner, Rupert and Pipa, Andrei V. and Hink, R{\"u}diger and Brandenburg, Ronny and Foest, R{\"u}diger and Geils, Judith and Sander, Aljoscha and Hoffmann, Florian and Matz, Daniel and Baars, Albert and Kesel, Antonia and Max, Alexander and Caspari, Ralf}, title = {Realization of Multifunctional Surfaces Containing MEMS-based DBD Plasma Actuators and Biomimetic Structures for Flow Manipulation}, series = {AIAA Aviation 2019 Forum, 2019, Dallas}, booktitle = {AIAA Aviation 2019 Forum, 2019, Dallas}, publisher = {American Institute of Aeronautics and Astronautics, Inc}, doi = {10.2514/6.2019-2999}, 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{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} } @inproceedings{EdlerHanschPrommesbergeretal., author = {Edler, Simon and Hansch, Walter 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 = {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.2018.8520214}, pages = {1-2}, abstract = {The influence of residual gas pressure on the characteristics of black-Silicon field emitter arrays in a high voltage triode setup is investigated. I-Vcharacteristics at different pressure levels show a decrease of emission current with rising pressure. This can be explained by an increase of the work function and charging of the emitter surface due to adsorbates. The initial characteristics can be restored by heating the FEA up to 110 °C during electron emission. This regeneration procedure enables an extension of the lifetime from about 20 h to 440 h at a residual gas pressure of 10 -5 mbar.}, language = {en} } @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{SilberbauerLindnerSchreiner, author = {Silberbauer, Theodor and Lindner, Matthias and Schreiner, Rupert}, title = {Charakterisierung der dielektrischen Barrierenentladung von Mikroplasmaaktuatoren in Abh{\"a}ngigkeit der Substratdicke}, series = {Intelligente Systeme und ihre Komponenten: Forschung und industrielle Anwendung : Fachbeitr{\"a}ge 2. Symposium Elektronik und Systemintegration ESI 2020}, booktitle = {Intelligente Systeme und ihre Komponenten: Forschung und industrielle Anwendung : Fachbeitr{\"a}ge 2. Symposium Elektronik und Systemintegration ESI 2020}, address = {Landshut}, pages = {64 -- 72}, language = {de} } @article{KrysztofMieraUrbańskietal., author = {Krysztof, Michał and Miera, Paweł and Urbański, Paweł and Grzebyk, Tomasz and Hausladen, Matthias and Schreiner, Rupert}, title = {Integrated silicon electron source for high vacuum microelectromechanical system devices}, series = {Journal of Vacuum Science \& Technology B}, volume = {42}, journal = {Journal of Vacuum Science \& Technology B}, number = {2}, publisher = {AIP Publishing}, issn = {2166-2746}, doi = {10.1116/6.0003385}, abstract = {The article presents the process of developing a silicon electron source designed for high-vacuum microelectromechanical system (HV MEMS) devices, i.e., MEMS electron microscope and MEMS x-ray source. Technological constraints and issues of such an electron source are explained. The transition from emitters made of carbon nanotubes to emitters made of pure silicon is described. Overall, the final electron source consists of a silicon tip emitter and a silicon gate electrode integrated on the same glass substrate. The source generates an electron beam without any carbon nanotube coverage. It generates a high and stable electron current and works after the final bonding process of an HV MEMS device.}, language = {en} } @article{SchreinerNaegeleKoerbletal., author = {Schreiner, Rupert and Naegele, Peter and K{\"o}rbl, M. and Groning, A. and Gentner, Jean-Louis and Schweizer, Heinz C.}, title = {Monolithically integrated tunable laterally coupled distributed-feedback lasers}, series = {Photonics Technology Letters}, volume = {13}, journal = {Photonics Technology Letters}, number = {12}, publisher = {IEEE}, doi = {10.1109/68.969880}, pages = {1277 -- 1279}, abstract = {A new method for fabrication of tunable InGaAsP-InP single-mode lasers without epitaxial overgrowth is reported. These devices show the advantage of a considerably simplified fabrication process compared to conventional tunable laser types. The lasers comprise an active Bragg reflector integrated with an uncorrugated separately pumped gain region. By adjusting the current through the Bragg reflector, the wavelength can be tuned between 1590.8 and 1595.2 nm.}, language = {en} } @inproceedings{BuchnerKaiserHausladenetal., author = {Buchner, Philipp and Kaiser, Alexander and Hausladen, Matthias and Bartl, Mathias and Bachmann, Michael and Schreiner, Rupert}, title = {Silicon Nanowire Field Emitters with Integrated Extraction Gates Using Benzocyclobutene as an Insulator}, series = {37th International Vacuum Nanoelectronics Conference (IVNC), 15-19 July 2024, Brno, Czech Republic}, booktitle = {37th International Vacuum Nanoelectronics Conference (IVNC), 15-19 July 2024, Brno, Czech Republic}, publisher = {IEEE}, doi = {10.1109/IVNC63480.2024.10652314}, pages = {1 -- 2}, abstract = {We are continuously improving the performance of our field emission electron sources. In this work a geometrically optimized design of electron sources with silicon nanowire field emitters on pillars was fabricated. This new design increased the packing density of the emitters by using a hexagonal arrangement of the pillars and a pillar spacing of 40 µm. Benzocyclobutene was used as the insulator material for an integrated (Cr/Ni) extraction gate. A modified fabrication process for the field emitters further improved reproducibility and reliability. An emission current of about 0.4 mA was measured for 30 minutes at an extraction voltage of 250 V and an anode voltage of 500 V. Electron transmission through the gate reached almost 100\%.}, language = {en} } @article{BerndtMuggliHeckeletal., author = {Berndt, Dominik and Muggli, Josef and Heckel, Robert and Rahiman, Mohd Fuad and Lindner, Matthias and Heinrich, Stephan and Pl{\"o}chinger, Heinz and Schreiner, Rupert}, title = {A Robust Miniaturized Gas Sensor for H₂ and CO₂ Detection Based on the 3ω Method}, series = {Sensors}, volume = {22}, journal = {Sensors}, number = {2}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/s22020485}, pages = {1 -- 17}, abstract = {Gas concentration monitoring is essential in industrial or life science areas in order to address safety-relevant or process-related questions. Many of the sensors used in this context are based on the principle of thermal conductivity. The 3ω-method is a very accurate method to determine the thermal properties of materials. It has its origin in the thermal characterization of thin solid films. To date, there have been very few scientific investigations using this method to determine the thermal properties of gases and to apply it to gas measurement technology. In this article, we use two exemplary gases (H2 and CO2) for a systematical investigation of this method in the context of gas analysis. To perform our experiments, we use a robust, reliable sensing element that is already well established in vacuum measurement technology. This helix-shaped thin wire of tungsten exhibits high robustness against chemical and mechanical influences. Our setup features a compact measurement environment, where sensor operation and data acquisition are integrated into a single device. The experimental results show a good agreement with a simplified analytical model and FEM simulations. The sensor exhibits a lower detection limit of 0.62\% in the case of CO2, and only 0.062\% in case the of H2 at an excitation frequency of 1 Hz. This is one of the lowest values reported in literature for thermal conductivity H2 sensors.}, language = {en} } @article{SchreinerKoerblGraebeldingeretal., author = {Schreiner, Rupert and K{\"o}rbl, M. and Gr{\"a}beldinger, H. and Gentner, Jean-Louis and Schweizer, H.}, title = {Laterally gain-coupled 1.57 [micro sign]m DFB lasers with chromium surface grating and self-aligned Ti/Pt/Au ohmic contact}, series = {Electronics Letters}, volume = {36}, journal = {Electronics Letters}, number = {7}, publisher = {The Institution of Engineering and Technology, IET}, issn = {0013-5194}, doi = {10.1049/el:20000500}, pages = {636 -- 637}, abstract = {A simple method for fabricating gain coupled DFB lasers with lateral surface chromium Bragg gratings and self-aligned low capacitance ohmic contacts is reported. These InGaAsP/InP lasers show monomode emission with a sidemode suppression ratio of 40 dB. For 243 µm long devices a continuous wave threshold current of 17 mA was measured at room temperature.}, 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} }