TY - JOUR A1 - Dams, Florian A1 - Navitski, Aliaksandr A1 - Prommesberger, Christian A1 - Serbun, Pavel A1 - Langer, Christoph A1 - Müller, Günter A1 - Schreiner, Rupert T1 - Homogeneous Field Emission Cathodes With Precisely Adjustable Geometry Fabricated by Silicon Technology JF - IEEE Transactions on Electron Devices N2 - 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. KW - cathodes KW - electron field emission KW - elemental semiconductors KW - Field emission (FE) cathodes KW - field emitter array (FEA) KW - miniaturized electron sources KW - oxidation KW - silicon KW - silicon tips KW - sputter etching Y1 - 2012 U6 - https://doi.org/10.1109/TED.2012.2206598 SN - 0018-9383 SN - 1557-9646 VL - 59 IS - 10 SP - 2832 EP - 2837 PB - IEEE ER - TY - CHAP A1 - Bornmann, Benjamin A1 - Mingels, Stephan A1 - Serbun, Pavel A1 - Lützenkirchen-Hecht, Dirk A1 - Müller, Güntner A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Dams, Florian A1 - Schreiner, Rupert T1 - Photosensitivity of electron field emission from B-doped Si-tip arrays T2 - 25th International Vacuum Nanoelectronics Conference (IVNC) ; Jeju, Korea (South), 09.07.2012 - 13.07.2012 N2 - 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. KW - boron KW - electron field emission KW - electron spectroscopy KW - elemental semiconductors KW - field emitter arrays KW - halogens KW - lamps KW - lighting KW - p-doped Si tips KW - photosensitivity KW - silicon KW - valence bands Y1 - 2012 SN - 978-1-4673-1984-3 SN - 978-1-4673-1983-6 SN - 978-1-4673-1982-9 U6 - https://doi.org/10.1109/IVNC.2012.6316980 SN - 2380-6311 SN - 2164-2370 SP - 1 EP - 2 PB - IEEE ER - TY - CHAP A1 - Langer, Christoph A1 - Prommesberger, Christian A1 - Dams, Florian A1 - Schreiner, Rupert T1 - Theoretical investigations into the field enhancement factor of silicon structures T2 - 25th International Vacuum Nanoelectronics Conference (IVNC) - Jeju, Korea (South), 09.- 13.07.2012 N2 - In order to optimize our field-emitting silicon structures, the influence of geometric parameters like aspect ratio, aperture angle and curvature on the field enhancement factor was investigated by finite element simulations. A universal geometric model consisting of a rounded triangle and elliptic curvatures was taken for modeling a variety of different silicon tip as well as ridge structures. Whereas, a high dependency of the field enhancement on the aperture angle was found, the simulations show that the elliptic curvature affects the field enhancement only marginal. KW - elemental semiconductors KW - field emitter arrays KW - field enhancement factor KW - finite element analysis KW - silicon KW - silicon field emitter Y1 - 2012 SN - 978-1-4673-1984-3 SN - 978-1-4673-1983-6 SN - 978-1-4673-1982-9 U6 - https://doi.org/10.1109/IVNC.2012.6316886 SN - 2380-6311 SN - 2164-2370 PB - IEEE CY - Piscataway, N.J. ER - TY - CHAP A1 - Schreiner, Rupert A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Dams, Florian A1 - Serbun, Pavel A1 - Bornmann, Benjamin A1 - Navitski, Aliaksandr A1 - Müller, Güntner T1 - Highly uniform and stable electron field emission from B-doped Si-tip arrays for applications in integrated vacuum microelectronic devices T2 - 25th International Vacuum Nanoelectronics Conference (IVNC) - Jeju, Korea (South), 09.07. - 13.07.2012 N2 - 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. KW - boron KW - circuit stability KW - elemental semiconductors KW - field emission ion microscopy KW - field emitter arrays KW - integrated optoelectronics KW - microfabrication KW - microsensors KW - optical switches KW - silicon tips Y1 - 2012 SN - 978-1-4673-1984-3 SN - 978-1-4673-1983-6 SN - 978-1-4673-1982-9 U6 - https://doi.org/10.1109/IVNC.2012.6316857 SN - 2380-6311 SN - 2164-2370 SP - 1 EP - 2 PB - IEEE CY - Piscataway, NJ. ER - TY - CHAP A1 - Serbun, Pavel A1 - Navitski, Aliaksandr A1 - Müller, Güntner A1 - Schreiner, Rupert A1 - Prommesberger, Christian A1 - Langer, Christoph A1 - Dams, Florian T1 - Scaling of the field emission current from B-doped Si-tip arrays T2 - 25th International Vacuum Nanoelectronics Conference (IVNC) ; Jeju, Korea (South), 09.07.2012 - 13.07.2012 N2 - 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. KW - Anodes KW - B-doped KW - boron KW - Current measurement KW - current scaling KW - electron field emission KW - elemental semiconductors KW - field emitter arrays KW - Iron KW - Nonhomogeneous media KW - silicon KW - Voltage control Y1 - 2012 SN - 978-1-4673-1984-3 SN - 978-1-4673-1983-6 SN - 978-1-4673-1982-9 U6 - https://doi.org/10.1109/IVNC.2012.6316965 SN - 2380-6311 SN - 2164-2370 SP - 1 EP - 2 PB - IEEE CY - Piscataway, N.J. ER -