Effect of electrode materials on the vacuum breakdown behaviors at nanoscale

As electronic and electro-mechanical devices with high integration density have been universally employed in many fields of science and engineering, the insulation failure under high electric field become one of the major factors limiting the performance of micro/nano systems. Herein, the pre-breakdown and breakdown characteristics of tungsten (W) and molybdenum (Mo) needle electrodes across a 100-nm vacuum gap were investigated. In the pre-breakdown process, the current linearly increased with the applied voltage. The field emission played a dominated role in the vicinity of the breakdown threshold. Furthermore, the breakdown threshold of W needle electrode was 19.5% higher than that of Mo needle electrode owing to a similar work function and a higher melting point of W needle electrode compared with Mo needle electrode. The study would be beneficial to the choice of materials and the reliability analysis of micro/nano devices.