A study of electronic transport through a nanoscale air film

This paper presents a simple model for predicting electrical conductivity of air with varying electrode separation and different moisture content present in air. Our system consists of a metallic thin film (Cu) coated sample and a needle tip in a box filled with air. A constant potential difference has been applied between the tip and the sample and electrical current is calculated for different air-gaps and for different humidity conditions using COMSOL Multiphysics software. The electric potential, electric field and current density in the region between the probe tip and sample have been presented. The numerical results showing the variation of terminal current as a function of gap separation and relative humidity are found to be analogous with theoretical prediction. This study will be useful for finding the optimal current in case of electric field induced scanning probe nanolithography techniques such as electrolithography [1].