@techreport{BackesBalkeBenerjeeetal., type = {Working Paper}, author = {Backes, Judith and Balke, Maurice and Benerjee, Marc and Beitzel, Knut and B{\"o}hm, Elisabeth and Brandt, Hanna and Brunner, Ulrich and B{\"u}ttner, Carl Christopher and Dyrna, Felix and Grossmann, Irmgard and G{\"u}hring, Thorsten and H{\"u}nnebeck, Sophia and K{\"a}hler, Michael and Kl{\"o}ckner, Nicole and Kopkow, Christian and Lehmann, Lars and Martetschl{\"a}ger, Frank and Mauch, Frieder and Michalk, Katrin and M{\"u}ller, Maike and M{\"u}ller-Rath, Ralf and Nolte, Philip and Pfingsten, Andrea and Prill, Robert and Schnetzke, Marc and Seckler, Martina}, title = {Subacromiales Impingment}, edition = {1. Aufl./Version 1.0 (02.05.2021)}, organization = {Deutsche Vereinigung f{\"u}r Schulter- und Ellbogenchirurgie e.V. und Deutsche Gesellschaft f{\"u}r Orthop{\"a}die und Orthop{\"a}dische Chirurgie, e.V.}, pages = {47}, language = {de} } @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} } @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} } @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{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} } @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} } @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{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} } @techreport{VoigtRadloffAyerleBraunetal., type = {Working Paper}, author = {Voigt-Radloff, Sebastian and Ayerle, Gertrud M. and Braun, Cordula and H{\"o}hl, Werner and Lauer, Norina and Lautenschl{\"a}ger, Sindy and Marotzki, Ulrike and Mattern, Elke and M{\"u}ller, Christian}, title = {Leitfaden zum Aufbau Praxisbasierter Forschungsnetzwerke (PBFN) in den Gesundheitsfachberufen}, language = {de} } @techreport{VoigtRadloffStemmerKorporaletal., type = {Working Paper}, author = {Voigt-Radloff, Sebastian and Stemmer, Renate and Korporal, Johannes and Horbach, Annegret and Ayerle, Gertrud M. and Sch{\"a}fers, Rainhild and Greening, Monika and Binnig, Marlis and Mattern, Elke and Heldmann, Patrick and Wasner, Mieke and Braun, Cordula and Lohkamp, Monika and Marotzki, Ulrike and Kraus, Elke and Oltman, Ren{\´e}e and M{\"u}ller, Christian and Corsten, Sabine and Lauer, Norina and Schade, Veronika and Kempf, Sabrina}, title = {Forschung zu komplexen Interventionen in der Pflege- und Hebammenwissenschaft und in den Wissenschaften der Physiotherapie, Ergotherapie und Logop{\"a}die}, doi = {10.6094/UNIFR/10702}, language = {de} } @techreport{VoigtRadloffStemmerBehrensetal., author = {Voigt-Radloff, Sebastian and Stemmer, Renate and Behrens, Johann and Horbach, Annegret and Ayerle, Gertrud M. and Sch{\"a}fers, Rainhild and Mattern, Elke and Heldmann, Patrick and Braun, Cordula and Marotzki, Ulrike and Kraus, Elke and George, Sabine and M{\"u}ller, Christian and Corsten, Sabine and Lauer, Norina and Schade, Veronika and Kempf, Sabrina and Binnig, Marlis and Wasner, Mieke}, title = {Forschung zu komplexen Interventionen in der Pflege- und Hebammenwissenschaft und in den Wissenschaften der Physiotherapie, Ergotherapie und Logop{\"a}die}, doi = {10.6094/UNIFR/2013/1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-8939}, pages = {57}, abstract = {Dieser forschungsmethodische Leitfaden behandelt folgende Themen: (1) Wissenschaftlicher Transfer von komplexen Interventionen inkl. Fragestellungen und Methoden von Machbarkeits-, Wirksamkeits- und Implementationsstudien. (2) Recherchestrategien zur Krankheitslast inkl. Folgen f{\"u}r Betroffene und Gesellschaft und Versorgungsstatus durch Gesundheitsfachberufe. (3) Pr{\"a}zisierung von Forschungsfragestellungen. (4) Evidenzrecherche, Evidenzmapping und Beurteilung der Evidenzlage. (5) F{\"o}rderm{\"o}glichkeiten von Forschungsprojekten. (6) Forschungsnetzwerke in den Gesundheitsfachberufen.}, language = {de} } @inproceedings{SelgradMuellerReintgesetal., author = {Selgrad, Kai and M{\"u}ller, Jonas and Reintges, Christian and Stamminger, Marc}, title = {Fast Shadow Map Rendering for Many-Lights Settings}, series = {Eurographics Symposium on Rendering - Experimental Ideas \& Implementations}, booktitle = {Eurographics Symposium on Rendering - Experimental Ideas \& Implementations}, editor = {Eisemann, Elmar and Fiume, Eugene}, publisher = {The Eurographics Association}, isbn = {978-3-03868-019-2}, doi = {10.2312/sre.20161208}, pages = {41 -- 48}, abstract = {n this paper we present a method to efficiently cull large parts of a scene prior to shadow map computations for many-lights settings. Our method is agnostic to how the light sources are generated and thus works with any method of light distribution. Our approach is based on previous work in culling for ray traversal to speed up area light sampling. Applied to shadow mapping our method works for high- and low-resolution shadow maps and, in contrast to previous work on many-lights rendering, does neither entail scene approximations nor imposes limits on light range, while still providing significant gains in performance. In contrast to standard culling methods shadow map rendering itself is sped up by a factor of 1.5 to 8.6 while the speedup of shadow map rendering, lookup and shading together ranges from 1.1 to 4.2}, 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} } @article{BornmannMingelsDamsetal., author = {Bornmann, Benjamin and Mingels, Stephan and Dams, Florian and Prommesberger, Christian and Schreiner, Rupert and L{\"u}tzenkirchen-Hecht, Dirk and M{\"u}ller, G{\"u}ntner}, title = {Electron spectrometer in adjustable triode configuration for photo-induced field emission measurements}, series = {The Review of scientific instruments}, volume = {83}, journal = {The Review of scientific instruments}, number = {1}, publisher = {American Institute of Physics}, address = {Melville, NY}, doi = {10.1063/1.3673475}, abstract = {We have constructed a new ultrahigh vacuum apparatus with a triode configuration for the systematic investigation of photo-induced field emission (PFE) from metallic or semiconducting cathodes. These are exposed to electric fields up to 400 MV∕m and laser irradiation by means of hole or mesh gates. Cathodes and gates are in situ exchangeable and adjustable with high precision to ensure a homogeneous extraction of electrons which are partially transmitted to the fixed electron spectrometer. Its hemispherical sector analyzer provides an energy resolution limit of 8 meV. The commissioning of the measurement system has been performed with a tungsten needle. Its temperature showed up in the high-energy tail of the electron spectrum, while its work function was derived from the spectral low-energy part combined with the integral current-voltage curve. First PFE measurements on B-doped Si-tip arrays yielded a small field emission current increase under green laser illumination. A shift and splitting of the energy spectra was observed which revealed different emission regimes as well as the photosensitivity of the cathode due to carrier excitation into the conduction band. For the full exploitation of the PFE system, a tunable laser over a wide eV-range is required.}, 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{SchreinerDamsPrommesbergeretal., author = {Schreiner, Rupert and Dams, Florian and Prommesberger, Christian and Bornmann, Benjamin and Serbun, Pavel and Navitski, Aliaksandr and M{\"u}ller, G{\"u}ntner}, title = {Silicon-based integrated field emission electron sources for sensor application}, series = {24th International Vacuum Nanoelectronics Conference (IVNC), 2011 : 18 - 22 July 2011, Wuppertal, Germany}, booktitle = {24th International Vacuum Nanoelectronics Conference (IVNC), 2011 : 18 - 22 July 2011, Wuppertal, Germany}, publisher = {IEEE}, address = {Piscataway, NJ}, pages = {19 -- 20}, abstract = {We report on the design, fabrication and characterization of p-type silicon field emitter arrays for the application in compact fast switchable electron sources. Since standard silicon technology has been used to prepare the devices, they can be easily integrated with other silicon based sensors and electronic components, too. The emitter arrays consist of approx. 3×105 tips per cm2, with a tip radius less than 20 nm. By using self-aligned processes, an integrated gate electrode with a diameter of  3 μm was placed concentrically around the tips. A mesh of silicon-beams with a grating period of 100 μm and beam width of 20 μm forms the anode of the electron source. A glass wafer (thickness 300 μm) acts as spacer between anode and Si-tip cathode. Characterization of the field emission properties of the emitter arrays was performed by high resolution field emission scanning microscopy. The emitter arrays exhibit a highly stable and very homogeneous emission. A maximum stable current of 0.1 μA per tip was found. A saturation level in the voltage current characteristics, which was found at around 10 nA, supports current stabilisation and will enable optical modulation of the emission current.}, 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 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} } @article{PfeiferMuellerPrantletal., author = {Pfeifer, Christian and M{\"u}ller, Michael and Prantl, Lukas and Berner, Arne and Dendorfer, Sebastian and Englert, Carsten}, title = {Cartilage labelling for mechanical testing in T-peel configuration}, series = {International Orthopaedics}, volume = {36}, journal = {International Orthopaedics}, number = {7}, publisher = {Springer}, doi = {10.1007/s00264-011-1468-3}, pages = {1493 -- 1499}, abstract = {PURPOSE: The purpose of this study was to find a suitable method of labelling cartilage samples for the measurement of distraction distances in biomechanical testing. METHODS: Samples of bovine cartilage were labelled using five different methods: hydroquinone and silver nitrate (AgNO3), potassium permanganate (KMnO4) with sodium thiosulphate (Na2S2O3), India ink, heat, and laser energy. After the labelling, we analysed the cartilage samples with regard to cytotoxity by histochemical staining with ethidiumbromide homodimer (EthD-1) and calcein AM. Furthermore, we tested cartilages labelled with India ink and heat in a T-peel test configuration to analyse possible changes in the mechanical behaviour between marked and unlabelled samples. RESULTS: Only the labelling methods with Indian ink or a heated needle showed acceptable results in the cytotoxity test with regard to labelling persistence, accuracy, and the influence on consistency and viability of the chondrocytes. In the biomechanical T-peel configuration, heat-labelled samples collapsed significantly earlier than unlabelled samples. CONCLUSION: Labelling bovine cartilage samples with Indian ink in biomechanical testing is a reliable, accurate, inexpensive, and easy-to-perform method. This labelling method influenced neither the biomechanical behaviour nor the viability of the tissue compared to untreated bovine cartilage.}, subject = {Knorpel}, 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} } @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} } @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} } @inproceedings{BauerZalkowMuelleretal., author = {Bauer, Judith and Zalkow, Frank and M{\"u}ller, Meinard and Dittmar, Christian}, title = {Evaluating the Impact of Prosody Feature Normalization on the Controllability of Pitch in Speech Synthesis}, series = {Elektronische Sprachsignalverarbeitung 2024, Tagungsband der 35. Konferenz, Regensburg, 6.-8. M{\"a}rz 2024}, booktitle = {Elektronische Sprachsignalverarbeitung 2024, Tagungsband der 35. Konferenz, Regensburg, 6.-8. M{\"a}rz 2024}, editor = {Baumann, Timo}, publisher = {TUDpress}, address = {Dresden}, isbn = {978-3-95908-325-6}, doi = {10.35096/othr/pub-7097}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-70976}, pages = {188 -- 195}, abstract = {Recent neural text-to-speech (TTS) models are able to synthesize highly natural speech signals using deep learning techniques. In practical applications, it can be desirable to have explicit control over the prosody (speech rate, fundamental frequency, and energy) of the synthesized speech. Such controllability can be achieved by adding prosody prediction modules, whose main purpose is to estimate plausible prosody features for each phoneme in the text input. This explicit modeling also allows for changing prosody features at inference time, consequently enabling the adjustment of the prosody in the synthesized audio. In this paper, we evaluate to which extent deliberate manipulation of such prosody features is reflected in the resulting speech audio. We focus particularly on changing the pitch (i.e., fundamental frequency) while applying different normalization strategies.}, language = {en} } @article{BirkenmaierDorniaLehleetal., author = {Birkenmaier, Clemens and Dornia, Christian and Lehle, Karla and M{\"u}ller, Thomas and Gruber, Michael Andreas and Philipp, Alois and Krenkel, Lars}, title = {Analysis of Thrombotic Deposits in Extracorporeal Membrane Oxygenators by High-resolution Microcomputed Tomography: A Feasibility Study}, series = {ASAIO Journal / American Society for Artificial Internal Organs}, volume = {66}, journal = {ASAIO Journal / American Society for Artificial Internal Organs}, number = {8}, publisher = {Lippincott Williams \& Wilkins}, issn = {1538-943X}, doi = {10.1097/MAT.0000000000001089}, pages = {922 -- 928}, abstract = {Coagulative disorders, especially clotting during extracorporeal membrane oxygenation, are frequent complications. Direct visualization and analysis of deposits in membrane oxygenators using computed tomography (CT) may provide an insight into the underlying mechanisms causing thrombotic events. However, the already established multidetector CT1 (MDCT) method shows major limitations. Here, we demonstrate the feasibility of applying industrial micro-CT (μCT) to circumvent these restrictions. Three clinically used membrane oxygenators were investigated applying both MDCT and μCT. The scans were analyzed in terms of clot volume and local clot distribution. As validation, the clot volume was also determined from the fluid volume, which could be filled into the respective used oxygenator compared to a new device. In addition, cross-sectional CT images were compared with crosscut oxygenators. Based on the μCT findings, a morphological measure (sphericity) for assessing clot structures in membrane oxygenators is introduced. Furthermore, by comparing MDCT and μCT results, an augmentation of the MDCT method is proposed, which allows for improved clot volume determination in a clinical setting.}, language = {en} } @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} }