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

Micro Hollow Cathode Discharge (MHCD) arrays, fabricated in silicon with Al 2 O 3 or titanium silicide- coated cathodes, have been investigated for use as high-current, coldcathode electron sources. When arranged as large arrays, micron-scale MHCD's have the potential to be used as electronbeam sources with current densities 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 Al 2 O 3 leads to increases in the plasma electron density and cathode operating lifetimes, respectively. Preliminary data show a significant increase in current density under identical operating conditions, using the alumina dielectric-coated cathodes as compared with bare-silicon baseline cathodes.