Experimental Studies of Gas Breakdown and Electron Emission for Nanoscale Gaps

Traditionally, gas breakdown is driven by Paschen’s law. Reducing gap distance to microscale creates high electric fields that strip electrons by field emission (FE), which adds space-charge that theoretically causes breakdown voltage (V_bd) to decrease linearly with decreasing gap distance d¹. With reducing d, electron emission ultimately transits from FE to space-charge limited emission², which may change breakdown behavior. This study reports experimental measurements for current as a function of voltage for d from 20 nm to 800 nm with various protrusion widths a to characterize field enhancement. At atmospheric pressure, V_bd decreases linearly with d down to ~200 nm for various a. For d < 200 nm, the slope of V_bd changes, possibly due to space-charge altering field emission prior to breakdown or due to reduced collisions because the electron mean free path exceeds d. At atmospheric pressure, V_bd ~ 5 V for d = 20 nm; V_bd ~ 300 V for d = 800 nm. We will also report the dependence of emission and breakdown on gap distance and pressure, and the implications on device design.

1. A. L. Garner, et al., IEEE Trans. Plasma Sci. 48, 808 (2020).

2. A. L. Garner, et al., J. Appl. Phys. 128, 210903 (2020).