Micro-Hollow Cathode Discharge (MHCD) MEMS arrays for high-current cold cathodes

Micro Hollow Cathode Discharge (MHCD) arrays, fabricated in silicon with Al2O3 - coated cathodes, have been investigated for use as high-current, cold-cathode electron sources. When arranged as large arrays, micron-scale MHCD´s have the potential to be used as electron-beam sources with currents up into the A-cm-2 range. Analysis, simulations and experimental data show that a quantum-mechanical tunneling current through the aluminum oxide cathode coating (when made thin enough) allows the DC operation of a MHCD at modest vacuum using Ar. The high secondary-electron emission, and low sputter yield, of Al2O3 leads to increases in the plasma electron density and cathode operating lifetimes, respectively. Preliminary data show a 35% increase in current, and a doubling in cathode operating lifetime, under identical operating conditions, using the alumina dielectric-coated cathodes as compared with bare-silicon baseline cathodes.