Comprehensive modeling of microscale gas breakdown under extremely high electric field

The breakdown physics of microscale gaps in micro-electromechanical systems has drawn significant attention due to its impact on device reliability and performance. Previous theoretical models that account for field emission on top of the Townsend mechanism have been developed to calculate the breakdown voltage of microgaps. In this work, we propose novel theoretical models for microscale breakdown based on the continuity equation of species, which incorporate additional physical mechanisms associated with extremely strong electric fields, including electron escape, ion impact ionization, and the dynamics of fast atoms. The multi- and single-valued breakdown curves are observed in helium and argon, respectively, which are confirmed by previous experiments and simulations. We elucidate the potential mechanisms underlying the emergence of direct current multi-valued curves and also demonstrate that smooth electrodes tend to excite distinctive strong-field processes. The results of this study offer a more comprehensive understanding of microdischarge breakdown physics, providing valuable guidance for the design and optimization of miniaturized gaseous electronic devices.