Statistical study of dc breakdown in a nanometer electrode gap and evidence of elementary mechanisms.

Abstract

Breakdown in Argon at nanoscale interelectrode gaps is studied to highlight the deviation from Paschen's law prediction. The discharge occurs between gold-plated electrodes in a setup similar to a planar configuration. A fast cutoff system allows the measurement of up to one hundred breakdowns for each experimental condition. A statistical study is then conducted on the probability distribution of breakdown voltages. The presence of two peaks in the breakdown distribution shows a competition between two different elementary discharge processes. One of it always occurs around a field value of 7.7×10^{8}V/m and does not seem to be affected by the pressure: this is the field emission breakdown mechanism. The other pressure-dependent mechanism is present only when the electrode gap is sufficiently large: this is the Townsend avalanche breakdown mechanism. The statistical method introduced in this work allows for a better interpretation of the processes involved in breakdown in submicrometer interelectrode spaces.