TY - CHAP A1 - Bachmann, Michael A1 - Dams, Florian A1 - Düsberg, Felix A1 - Hofmann, Martin A1 - Pahlke, Andreas A1 - Langer, Christoph A1 - Ławrowski, Robert Damian A1 - Prommesberger, Christian A1 - Schreiner, Rupert T1 - Control of the electron source current T2 - International Vacuum Nanoelectronics Conference (IVNC), 30th, 2017, Regensburg N2 - A control circuit to stabilize the flux of electrons transmitted through an extractor electrode is presented. By controlling the emission current a fluctuation with a standard deviation of 0.015% is observed. However, the achievable stability of the transmitted electron current is limited due to a variation of the extraction grid current ratio showing a standard deviation of 4.33%. By regulating the difference of the emission current and the extraction grid current an improved stability of the transmitted electron current down to a standard deviation of 0.280% is observed. Even with operation at 2 × 10 -5 mbar a standard deviation of 0.558% is achieved. KW - Standards KW - Circuit stability KW - Power system stability KW - Current measurement KW - Voltage measurement KW - Electron sources KW - Stability analysis Y1 - 2017 U6 - https://doi.org/10.1109/IVNC.2017.8051550 SP - 66 EP - 67 PB - IEEE ER - TY - JOUR A1 - Bachmann, Michael A1 - Düsberg, Felix A1 - Pahlke, Andreas A1 - Edler, Simon A1 - Schels, Andreas A1 - Herdl, Florian A1 - Ławrowski, Robert Damian A1 - Schreiner, Rupert T1 - High current silicon nanowire field emitter arrays JF - Journal of Vacuum Science & Technology B N2 - Arrays of n-doped silicon nanowire field emitters with a high aspect ratio are realized by a novel dry etching technique. Compared to the high current silicon emitters in the literature, the manufacturing process is much simpler and requires only a single photolithography step and two dry etching steps. The cathodes realized with this method exhibit a total current of 20 mA from an active area of 4×4 mm2, which is significantly higher than that for most known structures made from silicon and also represents good performance in comparison with other emitter types, e.g., carbon nanotubes. In addition to characterization in ultrahigh vacuum, measurements at 10−5 mbar are performed and compared with our recent silicon emitters. Compared to these cathodes, the structures with the nanowires exhibit at least two orders of magnitude higher current-carrying capability. Y1 - 2022 U6 - https://doi.org/10.1116/6.0001639 VL - 40 IS - 1 PB - AIP Publishing ER - TY - CHAP A1 - Ławrowski, Robert Damian A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Field Emission Arrays from Graphite Fabricated by Laser Micromachining T2 - 34th International Vacuum Nanoelectronics Conference (IVNC): 7/5/2021 - 7/9/2021, Lyon, France N2 - Arrays of 4x4 conical shaped emitters were directly structured by laser micromaching. Assembled as an electron source with a spacer and Si-grid, they were investigated by means of IV-measurement in ultra-high vacuum. The IV-measurements of the sample show integral emission currents up to 10 µA at a voltage of 1000 V (11 MV/m). Initially, an ideal FN-behaviour is noticeable. The deviation for higher voltage values in the FN-plot is caused by the change of the work function, which was proven by numerical calculations. KW - field emission array KW - graphite KW - laser micromachining Y1 - 2021 SN - 978-1-6654-2589-6 U6 - https://doi.org/10.1109/IVNC52431.2021.9600736 SP - 1 EP - 2 PB - IEEE ER - TY - CHAP A1 - Langer, Christoph A1 - Ławrowski, Robert Damian A1 - Prommesberger, Christian A1 - Dams, Florian A1 - Serbun, Pavel A1 - Bachmann, Michael A1 - Müller, Günter A1 - Schreiner, Rupert T1 - High aspect ratio silicon tip cathodes for application in field emission electron sources T2 - 2014 27th International Vacuum Nanoelectronics Conference (IVNC), 6-10 July 2014, Engelberg, Switzerland N2 - 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. KW - Current measurement KW - Etching KW - FABRICATION KW - field emission KW - field emitter array KW - GEOMETRY KW - Iron KW - Sensor arrays KW - silicon KW - silicon tip Y1 - 2014 U6 - https://doi.org/10.1109/IVNC.2014.6894824 SP - 222 EP - 223 PB - IEEE ER - TY - JOUR A1 - Bachmann, Michael A1 - Düsberg, Felix A1 - Langer, Christoph A1 - Herdl, Florian A1 - Bergbreiter, Lukas A1 - Dams, Florian A1 - Miyakawa, Natuski A1 - Eggert, Tobias A1 - Pahlke, Andreas A1 - Edler, Simon A1 - Prommesberger, Christian A1 - Ławrowski, Robert Damian A1 - Hausladen, Matthias A1 - Schreiner, Rupert T1 - Vacuum-sealed field emission electron gun JF - Journal of Vacuum Science & Technology B N2 - A compact vacuum-sealed field emission electron gun with an operation voltage below 5 kV is presented. With a 150 nm thick pyrolytic carbon membrane, a transmission of 40% at 5 kV is obtained. For more than 2500 h of continuous operation at an emission current of 100 nA, no significant increase (<50V ) and almost no degradation were found. From this measurement, a lifetime of more than 10 000 h at continuous operation with approximately a linear increase of the extraction voltage from about 545 V to about 730 V is predicted. This electron source enables application of field emitter arrays in poor vacuum or even ambient pressure. ACKNOWLEDGMENT This work was supported by the German Federal Ministry for Economic Affairs and Energy under Project No. ZF4081502GM8. C.P., R.L., M.H., and R.S. were supported by Grant No. ZF4562901GM8. Y1 - 2020 U6 - https://doi.org/10.1116/1.5139316 VL - 38 IS - 2 PB - AIP Publishing ER - TY - JOUR A1 - Ławrowski, Robert Damian A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Field emission arrays from graphite fabricated by laser micromachining JF - Journal of Vacuum Science & Technology B N2 - Laser micro structuring allows the manufacturing of conical shaped emitters on a graphitized carbon substrate without any additional treatment. Integral field emission measurements were performed in a diode configuration with a 50 µm mica spacer and a metalized Si-grid in a vacuum chamber at pressures of about 10-9 mbar. Emission currents up to 10 µA at a voltage of 1000 V (11 MV/m) with a positive current drift were observed for an array of 16 emitters. A strong modification of the emitter tip is noticeable after individual measurements. A comparable alteration of the surface is also achieved by an electrochemical treatment of the samples with a potassium hydroxide solution. However, the IV-measurements of such samples show higher onset voltages, but also higher integral emission currents. For all arrays an ideal FN behaviour is only noticeable at applied voltages below 625 V (7 MV/m). Numerical calculations indicate that the deviation in the FN-plot for higher voltage values is caused by the change of the effective work function. Y1 - 2022 U6 - https://doi.org/10.1116/6.0001547 VL - 40 IS - 2 PB - AIP Publishing ER - TY - CHAP A1 - Ławrowski, Robert Damian A1 - Langer, Christoph A1 - Prommesberger, Christian A1 - Dams, Florian A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Fabrication and simulation of silicon structures with high aspect ratio for field emission devices T2 - 2014 27th International Vacuum Nanoelectronics Conference (IVNC), 6-10 July 2014, Engelberg, Switzerland N2 - To obtain higher field enhancement factors of Si-tip structures, we present an improved fabrication process utilizing reactive-ion etching (RIE) with an inductively coupled plasma (ICP). In our design, a pillar under the tips is realized by a combination of RIE with ICP. With adjusted power settings (≈ 240 W) and step times (<; 5 s), vertical slopes with a low roughness of approximately 10 nm to 20 nm are possible. The remaining silicon is oxidized thermally to sharpen the emitters. A final tip radius of R <; 20 nm is obtained for the tips of the emitters. The pillar height HP can be mainly adjusted by the duration of the ICP-etching step. A total emitter height of H ≈ 6 μm with a pillar height of HP ≈ 5 μm is achieved. Simulations with COMSOL Multiphysics® are applied to calculate the field enhancement factor β. A two-dimensional model is used in rotational symmetry. In addition to the previous model, a pillar with a varying diameter ØP and height HP is added. A conventional emitter (H = 1 μm and R = 20 nm) placed on a pillar of the height HP ≈ 5 μm approximately results in a three times higher β-factor (β≈ 105). By decreasing the diameter ØP a slight increase of the β-factor is observed. However, the aspect ratio of the emitter mainly influences on the β-factor. KW - Anodes KW - CATHODES KW - FABRICATION KW - field emission KW - field emitter array KW - field enhancement factor KW - Iterative closest point algorithm KW - Lead KW - silicon tips Y1 - 2014 U6 - https://doi.org/10.1109/IVNC.2014.6894805 SP - 193 EP - 194 PB - IEEE ER - TY - CHAP A1 - Bachmann, Michael A1 - Dams, Florian A1 - Düsberg, F. A1 - Hofmann, Martin A1 - Pahlke, Andreas A1 - Langer, Christoph A1 - Ławrowski, Robert Damian A1 - Prommesberger, Christian A1 - Schreiner, Rupert T1 - Stability investigation of high aspect ratio n-type silicon field emitter arrays T2 - 2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China N2 - Electron sources based on silicon field emitter arrays, produced in processes based on semiconductor technology, are good candidates for a miniaturized X-ray source. A key parameter for this application is the stability of the X-ray photon flux and, thus, the emission current. In the present work we have investigated the influence of the residual gas pressure and a resistor in series on the emission stability of a high aspect ratio n-type silicon emitter array with hybrid extraction electrode. An increase of current fluctuations was found for pressures above 10-6 mbar. High resistances in series to the emitter array alter the emission characteristics, but greatly suppress spikes in the emission current and improve its stability. This, however, strongly depends on the bias point. The field enhancement factor is not affected by the resistance. In a long term measurement the emission current was found to be constant after an initial phase of degradation. KW - Current measurement KW - emission current stability KW - field emitter array KW - Field emitter arrays KW - RESISTANCE KW - Resistors KW - semiconductor field emission KW - silicon KW - silicon tips KW - Stability analysis KW - Thermal stability KW - XRF spectroscopy Y1 - 2015 U6 - https://doi.org/10.1109/IVNC.2015.7225584 SP - 204 EP - 205 PB - IEEE ER - TY - JOUR A1 - Ławrowski, Robert Damian A1 - Pirker, Luka A1 - Kaneko, Keita A1 - Kokubo, Hiroki A1 - Bachmann, Michael A1 - Ikuno, Takashi A1 - Remskar, Maja A1 - Schreiner, Rupert T1 - Field emission from nanotubes and flakes of transition metal dichalcogenides JF - Journal of Vacuum Science and Technology B N2 - Transition metal dichalcogenides such as MoS2 and WS2 are low-dimensional semiconductor materials. MoS2 and WS2 nanotubes and flakes were grown by a chemical transport reaction under a temperature gradient. I2 was used as a transport agent for previously synthesized MoS2 and WS2, respectively. These multilayered nanotubes are indirect bandgap semiconductors with a bandgap depending on their diameter. WS2 flakes were prepared by the sulfurization of thin WOx flakes. To increase the field enhancement of such low-dimensional structures by a higher aspect ratio, two approaches were examined: (a) the MoS2 and WS2 nanotubes were attached individually by a focused ion beam with Pt on dry etched n-type Si pillars and (b) the WS2 flakes were grown directly on the surface of the (n-type and p-type) Si pillars. Integral field emission measurements were performed in a diode configuration with a 50 μm mica spacer in a vacuum chamber at pressures of about 10−9 mbar. At a voltage of 900 V (18 MV/m), the integral emission current from the nanotubes is up to 11 μA for the lateral mounted MoS2 and about 1.3 μA (1.0 μA) for the upright mounted WS2 (MoS2). The onset voltage for a current of 1 nA is about 550 V for MoS2 and 500 V for WS2, respectively. The voltage conversion factor is in the range of 6 × 104–8 × 104 cm−1 for the nanotubes. The mounted MoS2 flakes show a field emission current of about 6 μA at 18 MV/m in contrast to the directly grown WS2 flakes, which show a pronounced saturation regime and, therefore, a lower emission current of about 0.5 μA is reached at 1500 V (25 MV/m). The WS2 flakes show a two times higher (1 × 105 cm−1) voltage conversion factor in comparison to the MoS2 flakes (5 × 104 cm−1). The extracted characteristics of the current-limiting part show a difference in the behavior of the extracted current-limiting characteristics between the lateral (linear) and upright mounted (exponential) nanotubes and the MoS2 flakes. In contrast, the WS2 flakes show charge carrier depletion effects. Y1 - 2020 U6 - https://doi.org/10.1116/1.5140474 VL - 38 IS - 3 SP - 032801 PB - AIP Publishing ER - TY - CHAP A1 - Serbun, Pavel A1 - Porshyn, Vitali A1 - Müller, Günter A1 - Mingels, Stephan A1 - Lützenkirchen-Hecht, Dirk A1 - Bachmann, Michael A1 - Düsberg, Felix A1 - Dams, Florian A1 - Hofmann, Martin A1 - Pahlke, Andreas A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Ławrowski, Robert Damian A1 - Schreiner, Rupert T1 - Field emission behavior of Au-tip-coated p-type Si pillar structures T2 - 29th International Vacuum Nanoelectronics Conference (IVNC), 2016, 11-15 July, Vancouver, BC, Canada N2 - 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. KW - field emission KW - p-type Si-pillar array KW - surface oxide effects KW - photoemission Y1 - 2016 U6 - https://doi.org/10.1109/IVNC.2016.7551516 SN - 2380-6311 SP - 181 EP - 182 PB - IEEE ER - TY - CHAP A1 - Schreiner, Rupert A1 - Langer, Christoph A1 - Prommesberger, Christian A1 - Ławrowski, Robert Damian A1 - Dams, Florian A1 - Bachmann, Michael A1 - Düsberg, F. A1 - Hofmann, Martin A1 - Pahlke, Andreas A1 - Serbun, Pavel A1 - Mingels, Stephan A1 - Müller, Günter T1 - Semiconductor field emission electron sources using a modular system concept for application in sensors and x-ray-sources T2 - 2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China N2 - 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. KW - Anodes KW - CATHODES KW - electron sources KW - GEOMETRY KW - Iron KW - Logic gates KW - semiconductor field emission KW - silicon Y1 - 2015 U6 - https://doi.org/10.1109/IVNC.2015.7225572 SP - 178 EP - 179 PB - IEEE ER - TY - CHAP A1 - Herdl, Florian A1 - Bachmann, Michael A1 - Wohlfartsstätter, Dominik A1 - Düsberg, Felix A1 - Dudeck, Markus A1 - Eder, Magdalena A1 - Meyer, Manuel A1 - Pahlke, Andreas A1 - Edler, Simon A1 - Schels, Andreas A1 - Hansch, Walter A1 - Schreiner, Rupert A1 - Wohlfartsstatter, Dominik A1 - Dusberg, Felix T1 - A novel current dependent field emission performance test T2 - 2021 34th International Vacuum Nanoelectronics Conference (IVNC): 5-9 July 2021, Lyon, France N2 - A current dependent performance test for comparison of different field emitter arrays is introduced. Statistical analysis is enabled due to a short measurement time and as a main feature the electric field shift, comparable to the degradation of the emitter is examined. Significance of the test method is shown by a comparison of field emitter arrays with different doping levels. KW - Current measurement KW - Field emitter arrays KW - Statistical analysis KW - Systematics KW - Time measurement KW - Tools KW - Vacuum systems Y1 - 2021 U6 - https://doi.org/10.1109/IVNC52431.2021.9600695 SP - 1 EP - 2 ER - TY - CHAP A1 - Schels, Andreas A1 - Edler, Simon A1 - Hansch, Walter A1 - Bachmann, Michael A1 - Herdl, Florian A1 - Dusberg, F. A1 - Eder, Magdalena A1 - Meyer, Manuel A1 - Dudek, M. A1 - Pahlke, Andreas A1 - Schreiner, Rupert ED - Purcell, Stephen ED - Mazellier, Jean-Paul T1 - Current dependent performance test used on different types of silicon field emitter arrays T2 - 2021 34th International Vacuum Nanoelectronics Conference (IVNC): 5-9 July 2021, Lyon, France N2 - A current dependent performance test is used to investigate the influence of doping and emitter geometry on the lifetime of silicon field emitter arrays. The measurements reveal an improved performance for lower n-type dopant concentrations. Furthermore, two new types of field emitters are introduced by slightly varying the original fabrication process [1]. The comparison shows superiority of tip like emitters over blade like structures. Y1 - 2021 SN - 978-1-6654-2589-6 U6 - https://doi.org/10.1109/IVNC52431.2021.9600787 SP - 1 EP - 2 PB - IEEE CY - Piscataway, NJ ER - TY - JOUR A1 - Schels, Andreas A1 - Herdl, Florian A1 - Hausladen, Matthias A1 - Wohlfartsstätter, Dominik A1 - Edler, Simon A1 - Bachmann, Michael A1 - Pahlke, Andreas A1 - Schreiner, Rupert A1 - Hansch, Walter T1 - Quantitative Field Emission Imaging for Studying the Doping-Dependent Emission Behavior of Silicon Field Emitter Arrays JF - Micromachines N2 - Field emitter arrays (FEAs) are a promising component for novel vacuum micro- and nanoelectronic devices, such as microwave power amplifiers or fast-switching X-ray sources. However, the interrelated mechanisms responsible for FEA degradation and failure are not fully understood. Therefore, we present a measurement method for quantitative observation of individual emission sites during integral operation using a low-cost, commercially available CMOS imaging sensor. The emission and degradation behavior of three differently doped FEAs is investigated in current-regulated operation. The measurements reveal that the limited current of the p-doped emitters leads to an activation of up to 55% of the individual tips in the array, while the activation of the n-type FEA stopped at around 30%. This enhanced activation results in a more continuous and uniform current distribution for the p-type FEA. An analysis of the individual emitter characteristics before and after a constant current measurement provides novel perspectives on degradation behavior. A burn-in process that trims the emitting tips to an integral current-specific ideal field enhancement factor is observed. In this process, blunt tips are sharpened while sharp tips are dulled, resulting in homogenization within the FEA. The methodology is described in detail, making it easily adaptable for other groups to apply in the further development of promising FEAs. Y1 - 2023 U6 - https://doi.org/10.3390/mi14112008 VL - 14 IS - 11 PB - MDPI ER - TY - CHAP A1 - Schels, Andreas A1 - Herdl, Florian A1 - Hausladen, Matthias A1 - Wohlfartsstätter, Dominik A1 - Bachmann, Michael A1 - Edler, Simon A1 - Düsberg, Felix A1 - Pahlke, Andreas A1 - Buchner, Philipp A1 - Schreiner, Rupert A1 - Hansch, Walter T1 - Beta Factor Mapping of Individual Emitting Tips During Integral Operation of Field Emission Arrays T2 - 2023 IEEE 36th International Vacuum Nanoelectronics Conference (IVNC), 10-13 July 2023, Cambridge, MA, USA N2 - Emission uniformity mappings of field emitter arrays provide important insight into degradation mechanisms, but are often laborious, non-integral, costly, or not quantifiable. Here, a low-cost Raspberry Pi HQ camera is used as an extraction anode to quantify the emission distribution in field emitter arrays. A verification measurement using controlled SEM electron beams proves, that current-voltage characteristics of individual emission sites can be determined by combining the integral electrical data with the image data. The characteristics are used to quantify the field enhancement factors of an 30x30 silicon field emitter array during integral operation. Comparison of the field enhancement factor distributions before and after a one-hour constant current operation at 1 µA shows an increase from 50 actively emitting tips before to 156 after the measurement. It is shown, that the distribution of field enhancement factors shifts towards lower values, due to the increasing degradation for high field enhancement tips, especially above 1500. KW - field emission KW - field emission imaging KW - field emission distribution KW - field enhancement factor KW - CMOS imaging KW - beta factor Y1 - 2023 SN - 979-8-3503-0143-4 U6 - https://doi.org/10.1109/IVNC57695.2023.10188957 SP - 224 EP - 226 PB - IEEE ER - TY - CHAP A1 - Hausladen, Matthias A1 - Buchner, Philipp A1 - Schels, Andreas A1 - Edler, Simon A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - An Integrated Field Emission Electron Source on a Chip Fabricated by Laser-Micromachining and Mems Technology T2 - 2023 IEEE 36th International Vacuum Nanoelectronics Conference (IVNC), 10-13 July 2023, Cambridge, MA, USA N2 - A silicon field emission electron source consisting of a cathode and a grid electrode has been fabricated by laser micromachining. The cathode features 21×21 tips on an area of 4×4 mm 2 , With a self-aligning MEMS technology for the aperture grid, a high electron transmission (99 %) was achieved. Onset voltages of 50…70 V were observed for an emission current of 1 nA. A stable emission current of 1 mA ± 1.3 % at an extraction voltage of 250 V was observed during a 30-min operation. KW - Apertures KW - Field Emission KW - Field Emission Array KW - Ions KW - Laser-Micromachining KW - Lasers KW - Micromechanical devices KW - Silicon KW - Silicon Field Emission Array KW - Steady-state KW - Vacuum systems Y1 - 2023 SN - 979-8-3503-0143-4 U6 - https://doi.org/10.1109/IVNC57695.2023.10189001 SP - 115 EP - 116 PB - IEEE ER - TY - CHAP A1 - Buchner, Philipp A1 - Hausladen, Matthias A1 - Schels, Andreas A1 - Herdl, Florian A1 - Edler, Simon A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - An Integrated Silicon Nanowire Field Emission Electron Source on a Chip with High Electron Transmission T2 - 2023 IEEE 36th International Vacuum Nanoelectronics Conference (IVNC), 10-13 July 2023, Cambridge, MA, USA N2 - Silicon nanowire field emission arrays (50 × 50 pillars) were fabricated on a silicon glass hybrid wafer. The glass acts both as the support for the whole structure and insulator between cathode and extraction grid. The extraction grid matches the emitter structures and is optically aligned and adhered to the emitter chip by a vacuum compatible epoxide adhesive. These chips exhibit an emission current of about 600 μA at an extraction voltage of 300 V. The electron transmission through the grid is above 80 %. 58-hour longtime measurements were conducted showing low degradation of the emission current and high stability of electron transmission. KW - Semiconductor device measurement KW - Stimulated emission KW - Optical device fabrication KW - Glass KW - Power system stability KW - Insulators KW - Electron optics Y1 - 2023 SN - 979-8-3503-0143-4 U6 - https://doi.org/10.1109/IVNC57695.2023.10188878 SP - 6 EP - 8 PB - IEEE ER - TY - CHAP A1 - Hausladen, Matthias A1 - Schels, Andreas A1 - Buchner, Philipp A1 - Bartl, Mathias A1 - Asgharzade, Ali A1 - Edler, Simon A1 - Wohlfartsstätter, Dominik A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Improved Method for Determining the Distribution of FEA Currents by Optical CMOS Sensors T2 - 37th International Vacuum Nanoelectronics Conference (IVNC), 15-19 July 2024, Brno, Czech Republic N2 - CMOS image sensors are utilized to determine the time- and spatially-resolved distribution of the electron emission of silicon field emission arrays. During initial experiments, rather low field emission currents already visibly damaged the sensor surface, altering the system accuracy over the measurement time. Therefore, we coated the sensor surface with copper for protection. In contrast to the original insulating surface, the Cu coating provides a conductive surface for incident electrons and improves heat dissipation in addition. This prevents localized surface charges and surface damages which stabilize the system accuracy. Y1 - 2024 U6 - https://doi.org/10.1109/IVNC63480.2024.10652543 SP - 1 EP - 2 PB - IEEE ER - TY - JOUR A1 - Bachmann, Michael A1 - Düsberg, Felix A1 - Pahlke, Andreas A1 - Edler, Simon A1 - Schels, Andreas A1 - Herdl, Florian A1 - Hausladen, Matthias A1 - Buchner, Philipp A1 - Schreiner, Rupert T1 - The “LED‐version” of the electron gun: An electron source for operation in ambient pressure environments based on silicon field emitter arrays JF - Vakuum in Forschung und Praxis N2 - We report on our progress to develop and optimize electron sources for practical applications. A simple fabrication process is introduced based on a wafer dicing saw and a wet chemical etch step without the need for a clean room. Due to the formation of crystal facets the samples show a homogeneous geometry throughout the array. Characterization techniques are developed to systematically compare various arrays. A very defined measurement procedure based on current controlled IV-sweeps as well as lifetime measurements at various currents is proposed. To investigate the current distribution in the array a commercial CMOS detector is used and shows the potential for in depth analysis of the arrays. Finally, a compact hermetically sealed housing is presented enabling electron generation in atmospheric pressure environments. Y1 - 2023 U6 - https://doi.org/10.1002/vipr.202300801 VL - 35 IS - 3 SP - 32 EP - 37 PB - Wiley ER - TY - JOUR A1 - Hausladen, Matthias A1 - Schels, Andreas A1 - Buchner, Philipp A1 - Bartl, Mathias A1 - Asgharzade, Ali A1 - Edler, Simon A1 - Wohlfartsstätter, Dominik A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Measurement of field emission array current distributions by metal-coated CMOS image sensors JF - Journal of Vacuum Science & Technology B N2 - A CMOS image sensor is utilized to determine the time- and spatially resolved distribution of the total electron emission current of a silicon field emission array. The sensor measures electron emission without the need for phosphorus screens or scintillators as converters. However, in initial experiments, rather low field emission currents of several hundreds of nanoamperes per emitter already damaged the sensor surface, which altered the systems’ signal response over the measurement time. In consequence, we coated the CMOS sensor surface with a Cu layer for surface protection. In contrast to the original insulating surface, Cu is an excellent current- and heat-conductor, which avoids lens charging by providing a conductive path for incident electrons and has an improved heat dissipation capability. Measurements using a segmented field emission cathode with four individually addressable tips demonstrate a consistent correlation between the emission current and the sensor signal of the metal-coated image sensor. Furthermore, the characterization of a field emission array showed that single tip emission currents of up to 12 μA per tip are measurable without discernible damage effects of the sensor’s surface. KW - Bremsstrahlung KW - Laser micromachining KW - Image sensors KW - Field emitter arrays Y1 - 2024 U6 - https://doi.org/10.1116/6.0004074 VL - 42 IS - 6 PB - AIP Publishing ER - TY - JOUR A1 - Hausladen, Matthias A1 - Schels, Andreas A1 - Asgharzade, Ali A1 - Buchner, Philipp A1 - Bartl, Mathias A1 - Wohlfartsstätter, Dominik A1 - Edler, Simon A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Investigation of Influencing Factors on the Measurement Signal of a CMOS Image Sensor for Measuring Field Emission Currents JF - Sensors Y1 - 2025 U6 - https://doi.org/10.3390/s25051529 N1 - Corresponding author der OTH Regensburg: Matthias Hausladen VL - 25 IS - 5 PB - MDPI ER - TY - CHAP A1 - Bartl, Mathias A1 - Hausladen, Matthias A1 - Asgharzade, Ali A1 - Buchner, Philipp A1 - Krysztof, Michal A1 - Knápek, Alexandr A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - Experimental method for investigation of the emission pattern characteristics of individual field emission tips using a CMOS image sensor T2 - 38th International Vacuum Nanoelectronics Conference (IVNC) N2 - The emission pattern characteristics of individual silicon field emission tips were investigated using a CMOS image sensor. The quality of the image was improved by spatial and temporal averaging, so that individual emission centers could be identified and their temporal changes investigated. By mapping the emission current onto the image, the distribution of the current density on the image sensor could be calculated. KW - CMOS image sensors KW - Silicon KW - Current density KW - Nanoelectronics Y1 - 2025 U6 - https://doi.org/10.1109/IVNC65669.2025.11121040 PB - IEEE ER - TY - CHAP A1 - Asgharzade, Ali A1 - Bartl, Mathias A1 - Hausladen, Matthias A1 - Chen, Yang A1 - Buchner, Philipp A1 - Edler, Simon A1 - Bachmann, Michael A1 - She, Juncong A1 - Schreiner, Rupert T1 - Investigation on the influence of internal voltage drops on the emission behavior of silicon field emission arrays using CMOS image sensor T2 - 38th International Vacuum Nanoelectronics Conference (IVNC) N2 - In this paper we report on an improved measurement and analysis method for determining the emission current distribution of field emitter arrays with CMOS sensors. It can also be used for field emission arrays where not all surfaces of the emitters are at the same electrical potential (e.g. for p-doped Si tips, where a strong current saturation occurs). To demonstrate the functionality of this method, a n-doped field emission array was measured using a variable external series resistance. Brightness variations in emission spots were analyzed to re-calculate the known series resistances for comparison. The re-calculated value is in good agreement with the actual value of the resistance. This method offers a quantitative approach to assess internal voltage drop effects on field emission using optical readout KW - field emission imaging KW - field emission KW - CMOS sensor Y1 - 2025 U6 - https://doi.org/10.1109/IVNC65669.2025.11120937 PB - IEEE ER - TY - JOUR A1 - Buchner, Philipp A1 - Hausladen, Matthias A1 - Bartl, Mathias A1 - Bachmann, Michael A1 - Schreiner, Rupert T1 - High current field emission from Si nanowires on pillar structures JF - Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics N2 - We investigate the influence of the geometry and doping level on the performance of n-type silicon nanowire field emitters on silicon pillar structures. Therefore, multiple cathodes with 50 by 50 pillar arrays (diameter: 5 μm, height: 30 μm, spacing: 50 μm) were fabricated and measured in diode configuration. In the first experiment, we compared two geometry types using the same material. Geometry 1 is black silicon, which is a highly dense surface covering a forest of tightly spaced silicon needles resulting from self-masking during a plasma etching process of single crystal silicon. Geometry 2 are silicon nanowires, which are individual spaced-out nanowires in a crownlike shape resulting from a plasma etching process of single crystal silicon. In the second experiment, we compared two different silicon doping levels [n-type (P), 1–10 and <0.005 Ω cm] for the same geometry. The best performance was achieved with lower doped silicon nanowire samples, emitting 2 mA at an extraction voltage of 1 kV. The geometry/material combination with the best performance was used to assemble an integrated electron source. These electron sources were measured in a triode configuration and reached onset voltages of about 125 V and emission currents of 2.5 mA at extraction voltages of 400 V, while achieving electron transmission rates as high as 85.0%. KW - Doping KW - Electron sources KW - Nanowires KW - Plasma processing KW - Field emitter arrays KW - Triodes KW - Semiconductors Y1 - 2024 U6 - https://doi.org/10.1116/6.0003384 SN - 2166-2754 VL - 42 IS - 2 PB - AIP ER - TY - JOUR A1 - Tan, Jing Jie A1 - Schreiner, Rupert A1 - Hausladen, Matthias A1 - Asgharzade, Ali A1 - Edler, Simon A1 - Bartsch, Julian A1 - Bachmann, Michael A1 - Schels, Andreas A1 - Kwan, Ban-Hoe A1 - Ng, Danny Wee-Kiat A1 - Hum, Yan-Chai T1 - SiMiC: Context-aware silicon microstructure characterization using attention-based convolutional neural networks for field-emission tip analysis JF - Journal of Vacuum Science & Technology B N2 - Accurate characterization of silicon microstructures is essential for advancing microscale fabrication, quality control, and device performance. Traditional analysis using scanning electron microscopy (SEM) often requires labor-intensive, manual evaluation of feature geometry, limiting throughput and reproducibility. In this study, we propose SiMiC: Context-aware Silicon Microstructure Characterization Using Attention-based Convolutional Neural Networks for Field-Emission Tip Analysis. By leveraging deep learning, our approach efficiently extracts morphological features—such as size, shape, and apex curvature—from SEM images, significantly reducing human intervention while improving measurement consistency. A specialized dataset of silicon-based field-emitter tips was developed, and a customized convolutional neural network architecture incorporating attention mechanisms was trained for multiclass microstructure classification and dimensional prediction. Comparative analysis with classical image processing techniques demonstrates that SiMiC achieves high accuracy while maintaining interpretability. The proposed framework establishes a foundation for data-driven microstructure analysis directly linked to field-emission performance, opening avenues for correlating emitter geometry with emission behavior and guiding the design of optimized cold-cathode and SEM electron sources. The related dataset and algorithm repository that could serve as a baseline in this area can be found at https://research.jingjietan.com/?q=SIMIC. KW - Field emitter arrays KW - Quality assurance KW - Convolutional neural network KW - Deep learning KW - Image processing KW - Machine learning KW - Cold cathodes KW - Scanning electron microscopy KW - Electron sources KW - Chemical elements Y1 - 2025 U6 - https://doi.org/10.1116/6.0005068 VL - 43 IS - 6 PB - AVS ER -