@article{HausladenSchelsBuchneretal., author = {Hausladen, Matthias and Schels, Andreas and Buchner, Philipp and Bartl, Mathias and Asgharzade, Ali and Edler, Simon and Wohlfartsst{\"a}tter, Dominik and Bachmann, Michael and Schreiner, Rupert}, title = {Measurement of field emission array current distributions by metal-coated CMOS image sensors}, series = {Journal of Vacuum Science \& Technology B}, volume = {42}, journal = {Journal of Vacuum Science \& Technology B}, number = {6}, publisher = {AIP Publishing}, doi = {10.1116/6.0004074}, abstract = {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.}, language = {en} } @article{HausladenBuchnerBartletal., author = {Hausladen, Matthias and Buchner, Philipp and Bartl, Mathias and Bachmann, Michael and Schreiner, Rupert}, title = {Integrated multichip field emission electron source fabricated by laser-micromachining and MEMS technology}, series = {Journal of Vacuum Science \& Technology B}, volume = {42}, journal = {Journal of Vacuum Science \& Technology B}, number = {1}, publisher = {AIP Publishing}, doi = {10.1116/6.0003233}, abstract = {In this work, high-current field emission electron source chips were fabricated using laser-micromachining and MEMS technology. The resulting chips were combined with commercially available printed circuit boards (PCBs) to obtain a multichip electron source. By controlling the separate electron sources using an external current control circuit, we were able to divide the desired total current evenly across the individual chips deployed in the PCB-carrier. In consequence, we were able to show a decreased degradation due to the reduced current load per chip. First, a single electron source chip was measured without current regulation. A steady-state emission current of 1 mA with a high stability of ±1.3\% at an extraction voltage of 250 V was observed. At this current level, a mean degradation slope of -0.7 μA/min with a nearly perfect transmission ratio of 99\% ± 0.4\% was determined. The measurements of a fully assembled multichip PCB-carrier electron source, using a current control circuit for regulation, showed that an even distribution of the desired total current led to a decreased degradation. This was determined by the increase in the required extraction voltage over time. For this purpose, two current levels were applied to the electron source chips of the PCB-carrier using an external current control circuit. First, 300 μA total current was evenly distributed among the individual electron source chips followed by the emission of 300 μA per electron source chip. This allows the observation of the influence of a distributed and nondistributed total current, carried by the electron source chips. Thereby, we obtained an increase in the mean degradation slope from +0.011 V/min (300 μA distributed) to +0.239 V/min (300 μA per chip), which is approximately 21 times higher. Moreover, our current control circuit improved the current stability to under 0.1\% for both current levels, 300 μA distributed and 300 μA per chip.}, language = {en} } @article{LangerBomkeHausladenetal., author = {Langer, Christoph and Bomke, Vitali and Hausladen, Matthias and Ławrowski, Robert Damian and Prommesberger, Christian and Bachmann, Michael and Schreiner, Rupert}, title = {Silicon Chip Field Emission Electron Source Fabricated by Laser Micromachining}, series = {Journal of Vacuum Science \& Technology B}, volume = {38}, journal = {Journal of Vacuum Science \& Technology B}, number = {1}, publisher = {AIP Publishing}, doi = {10.1116/1.5134872}, abstract = {The components for a silicon chip electron source were fabricated by laser micromachining using pulsed laser ablation and wet chemical cleaning and etching dips. The field emission electron source consists of a silicon field emission cathode with 4 × 4 conical shaped emitters with a height of 250 μm and a tip radius of about 50 nm, a 50 μm thick laser-structured mica spacer, and a silicon grid electrode with a grid periodicity of 200 μm and a bar width of 50 μm. These three components are combined to a single chip with the size of 14 × 10 mm2 and the thickness of 1 mm to form the electron source. Several of these devices were characterized in ultrahigh vacuum. Onset voltages of about 165 V and cathode currents of about 15 μA for voltages lower than 350 V were observed. Operating the electron source with an anode voltage of 500 V and an extraction grid voltage of 300 V yielded a cathode current of 4.5 μA ± 8.9\%, an anode current of 4.0 μA ± 9.6\%, and a corresponding grid transmittance of 89\%. Regulating the anode current by the extraction grid voltage, an extremely stable anode current of 5.0 μA ± 0.017\% was observed. A long-term measurement over 120 h was performed, and no significant degradation or failure was observed.}, language = {en} }