Highly nonlinear varistors fabricated by hot-dipping tin oxide thin films in Ta2O5 powder at different temperatures

Abstract

This work proposed a smart approach to fabricate highly nonlinear SnOx-Ta2O5 thin film varistors. During processing, tin oxide films in nanoscaled thickness were firstly deposited onto electrically conducting silicon wafers through radio frequency magnetron sputtering a sintered tin oxide ceramic target; and then, the obtained films were hot-dipped in Ta2O5 powder in a Muffle oven for 60min at different temperatures. With the hot-dipping temperature increased from 300 to 800°C, the nonlinear coefficient of the samples increased first and then decreased, reaching the maximum of 16.8 at 600°C, which is a record in all the reported SnO2-based varistors and comparable with those of the most extensively investigated and commonly commercially applied ZnO-based ceramic varistors. Correspondingly, the leakage current decreased first and then increased, obtaining the minimum of 4.1mA/cm2. Besides, the breakdown electric field increased first and then decreased, presenting the maximum of 0.0313V/nm. Such nanoscaled thin film varistors would be promising in electrical and electronic devices working in low-voltage.