TY - JOUR A1 - Schels, Andreas A1 - Edler, Simon A1 - Herdl, Florian A1 - Hansch, Walter A1 - Bachmann, Michael A1 - Ritter, Daniela A1 - Dudeck, Markus A1 - Duesberg, Felix A1 - Meyer, Manuel A1 - Pahlke, Andreas A1 - Hausladen, Matthias A1 - Buchner, Philipp A1 - Schreiner, Rupert T1 - In situ quantitative field emission imaging using a low-cost CMOS imaging sensor JF - Journal of Vacuum Science & Technology B N2 - 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. KW - ARRAYS KW - ELECTRON-EMISSION KW - EMITTERS KW - FakANK Y1 - 2022 U6 - https://doi.org/10.1116/6.0001551 VL - 40 IS - 1 PB - AIP Publishing ER - TY - JOUR A1 - Edler, Simon A1 - Schels, Andreas A1 - Herdl, Florian A1 - Hansch, Walter A1 - Bachmann, Michael A1 - Dudeck, Markus A1 - Duesberg, Felix A1 - Pahlke, Andreas A1 - Hausladen, Matthias A1 - Buchner Philipp, A1 - Schreiner, Rupert T1 - Origin of the current saturation level of p-doped silicon field emitters JF - Journal of Vacuum Science & Technology B N2 - 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. KW - EMISSION KW - GROWTH KW - NATIVE-OXIDE Y1 - 2022 U6 - https://doi.org/10.1116/6.0001554 VL - 40 IS - 1 PB - AIP Publishing ER - TY - CHAP A1 - Tschurtschenthaler, Karl A1 - Krenkel, Lars A1 - Schreiner, Rupert T1 - Mechano-optical micro pillar sensor for biofluidmechanic wall shear stress measurements T2 - 25th Congress of the European Society of Biomechanics (ESB), July 7-10, 2019, Vienna, Austria Y1 - 2019 UR - https://esbiomech.org/conference/archive/2019vienna/Contribution_608.pdf ER - TY - JOUR A1 - Bieker, Johannes A1 - Roustaie, Farough A1 - Schlaak, Helmut F. A1 - Langer, Christoph A1 - Schreiner, Rupert A1 - Lotz, Marcel A1 - Wilfert, Stefan T1 - Field emission characterization of in situ deposited gold nanocones with variable cone densities JF - Journal of Vacuum Science and Technology B N2 - 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. Y1 - 2018 U6 - https://doi.org/10.1116/1.5009504 VL - 36 IS - 2 PB - AIP Publishing ER - TY - CHAP A1 - Dams, Florian A1 - Schreiner, Rupert T1 - A high thermal resistance MEMS-based Pirani vacuum sensor chip T2 - Smart sensors, actuators and MEMS VI : 24 - 26 April 2013, Grenoble, France / [part of SPIE microtechnologies] N2 - 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. Y1 - 2013 U6 - https://doi.org/10.1117/12.2017345 PB - SPIE CY - Bellingham, Wash. ER - TY - GEN A1 - Düsberg, Felix A1 - Bachmann, Michael A1 - Edler, Simon A1 - Pahlke, Andreas A1 - Langer, Christoph A1 - Prommesberger, Christian A1 - Schreiner, Rupert A1 - Bunert, Erik A1 - Wendt, Cornelius A1 - Zimmermann, Stefan T1 - Novel Non-Radiative Electron Source T2 - 43rd International Symposium of Capillary Chromatography & 16h GC x GC Symposium 2019 N2 - 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. Y1 - 2019 ER - TY - CHAP A1 - Berndt, Dominik A1 - Lindner, Matthias A1 - Schreiner, Rupert A1 - Pipa, Andrei V. A1 - Hink, Rüdiger A1 - Brandenburg, Ronny A1 - Foest, Rüdiger A1 - Geils, Judith A1 - Sander, Aljoscha A1 - Hoffmann, Florian A1 - Matz, Daniel A1 - Baars, Albert A1 - Kesel, Antonia A1 - Max, Alexander A1 - Caspari, Ralf T1 - Realization of Multifunctional Surfaces Containing MEMS-based DBD Plasma Actuators and Biomimetic Structures for Flow Manipulation T2 - AIAA Aviation 2019 Forum, 2019, Dallas Y1 - 2019 U6 - https://doi.org/10.2514/6.2019-2999 PB - American Institute of Aeronautics and Astronautics, Inc ER - TY - CHAP A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Schreiner, Rupert T1 - Stable and low noise field emission from single p-type Si-tips T2 - International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan N2 - 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. KW - field emission KW - p-type Si-tips KW - gate-electrode KW - emission stability KW - low current fluctuations Y1 - 2018 U6 - https://doi.org/10.1109/IVNC.2018.8520018 PB - IEEE ER - TY - CHAP A1 - Lindner, Matthias A1 - Berndt, Dominik A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Schreiner, Rupert T1 - Field emission assisted micro plasma discharges at vacuum and atmospheric pressures T2 - 31st International Vacuum Nanoelectronics Conference (IVNC), 2018, Kyoto, Japan N2 - 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%. Y1 - 2018 U6 - https://doi.org/10.1109/IVNC.2018.8520181 ER - TY - CHAP A1 - Berndt, Dominik A1 - Lindner, Matthias A1 - Tschurtschenthaler, Karl A1 - Langer, Christoph A1 - Schreiner, Rupert T1 - Miniaturized Plasma Actuator Flow Measurements by MEMS-Based Thermal Conductivity Sensors T2 - MDPI Proceedings of Eurosensors 2018, 9-12 September, Graz N2 - 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. KW - thermal conductivity sensors; plasma actuators; surface hotfilms; sensors for aerospace Y1 - 2018 U6 - https://doi.org/10.3390/proceedings2130939 VL - Vol.13 IS - 2 ER - TY - CHAP A1 - Edler, Simon A1 - Hansch, Walter A1 - Prommesberger, Christian A1 - Schreiner, Rupert T1 - Influence of adsorbates on the performance of a field emitter array in a high voltage triode setup T2 - International Vacuum Nanoelectronics Conference (IVNC), 31st, 2018, Kyoto, Japan N2 - 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. KW - semiconductor field emission KW - field emitter array KW - silicon tips KW - emission current stability Y1 - 2018 U6 - https://doi.org/10.1109/IVNC.2018.8520214 PB - IEEE ER - TY - JOUR A1 - Berndt, Dominik A1 - Muggli, Josef A1 - Wittwer, Franz A1 - Langer, Christoph A1 - Heinrich, Stephan A1 - Knittel, Thorsten A1 - Schreiner, Rupert T1 - MEMS-based thermal conductivity sensor for hydrogen gas detection in automotive applications JF - Sensors and Actuators A: Physical N2 - 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. Y1 - 2020 U6 - https://doi.org/10.1016/j.sna.2019.111670 VL - 305 IS - April PB - Elsevier ER - TY - CHAP A1 - Silberbauer, Theodor A1 - Lindner, Matthias A1 - Schreiner, Rupert T1 - Charakterisierung der dielektrischen Barrierenentladung von Mikroplasmaaktuatoren in Abhängigkeit der Substratdicke T2 - Intelligente Systeme und ihre Komponenten: Forschung und industrielle Anwendung : Fachbeiträge 2. Symposium Elektronik und Systemintegration ESI 2020 Y1 - 2020 UR - https://nbn-resolving.org/urn:nbn:de:bvb:860-opus4-2130 N1 - Die Fachtagung, geplant für den 01. April 2020 an der Hochschule Landshut, wurde aufgrund der Corona-Pandemie abgesagt, die eingereichten Fachbeiträge im Tagungsband 2. Symposium Elektronik und Systemintegration ESI 2020: "Intelligente Systeme und ihre Komponenten: Forschung und industrielle Anwendung" veröffentlicht. Hrsg.: Artem Ivanov, Marc Bicker und Peter Patzelt. Hochschule Landshut, 2020, ISBN 978-3-9818439-4-1. SP - 64 EP - 72 CY - Landshut ER -