TY - JOUR A1 - Mingels, S. A1 - Porshyn, V. A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Schreiner, Rupert A1 - Lützenkirchen-Hecht, Dirk A1 - Müller, Günter T1 - Photosensitivity of p-type black Si field emitter arrays JF - Journal of Applied Physics N2 - 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. Y1 - 2016 U6 - https://doi.org/10.1063/1.4948328 VL - 119 IS - 16 ER - TY - CHAP A1 - Mingels, S. A1 - Porshyn, V. A1 - Serbun, Pavel A1 - Lützenkirchen-Hecht, Dirk A1 - Müller, Günter A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Schreiner, Rupert A1 - Lutzenkirchen-Hecht, Dirk T1 - Photo-enhanced field emission properties of p-doped black Si arrays T2 - 2016 29th International Vacuum Nanoelectronics Conference (IVNC), 11-15 July 2016, Vancouver, BC, Canada N2 - 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. KW - black Si KW - Decision support systems KW - photo-enhanced field emission Y1 - 2016 U6 - https://doi.org/10.1109/IVNC.2016.7551447 SP - 1 EP - 2 PB - IEEE ER - TY - CHAP A1 - Ławrowski, Robert Damian A1 - Langer, Christoph A1 - Prommesberger, Christian A1 - Schreiner, Rupert A1 - Mingels, S. A1 - Porshyn, V. A1 - Serbun, Pavel A1 - Müller, Günter T1 - Field emission from surface textured GaN with buried double-heterostructures T2 - 2015 28th International Vacuum Nanoelectronics Conference (IVNC), 13-17 July 2015, Guangzhou, China N2 - 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. KW - CATHODES KW - Current measurement KW - Electric fields KW - field emission KW - Gallium nitride KW - GaN KW - Iron KW - Light emitting diodes KW - photoemission KW - Surface texture Y1 - 2015 U6 - https://doi.org/10.1109/IVNC.2015.7225548 SP - 106 EP - 107 PB - IEEE ER - TY - CHAP A1 - Schreiner, Rupert A1 - Langer, Christoph A1 - Prommesberger, Christian A1 - Mingels, S. A1 - Serbun, Pavel A1 - Müller, Güntner T1 - Field emission from surface textured extraction facets of GaN light emitting diodes T2 - 26th International Vacuum Nanoelectronics Conference (IVNC), 8-12 July 2013, Roanoke, VA, USA N2 - 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 (Øanode= 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. KW - Gallium nitride KW - Iron KW - Light emitting diodes KW - Cathodes KW - Surface texture KW - Surface waves KW - Photonics Y1 - 2013 U6 - https://doi.org/10.1109/ivnc.2013.6624721 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, M. A1 - Pahlke, A. A1 - Serbun, Pavel A1 - Mingels, S. 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 - Serbun, Pavel A1 - Porshyn, V. A1 - Müller, Günter A1 - Mingels, S. 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 -