Measurements of geometric enhancement factors for silicon nanopillar cathodes using a scanning tunneling microscope

High-density silicon nanopillar cathodes were fabricated using a self-assembling colloidal gold etch mask. Scanning tunneling microscopy experiments were performed to locate individual nanopillars and to investigate their field emission properties. Emission characteristics were obtained over a range of fixed separations from the nanopillar apex, allowing the empirical determination of the geometric field enhancement factors from the resulting Fowler–Nordheim plots. The geometric enhancement factors were found to increase dramatically for decreasing anode–cathode separation and the rate of increase is dependent on the nanopillar geometry.