Varistors made of indium tin oxide∕Si multilayers on p-type GaN substrates

Abstract

Varistors are important devices in the prevention of electric circuits from electric surges or in the stabilization of the operation current. Instead of the conventional granular type, varistors consisting of conductor/semiconductor multilayers grown on p-type semiconductor substrates are developed. In this work, the conductor used is indium tin oxide (ITO), the semiconductor is Si and the substrate is of p-type GaN. It was found that symmetric and nonlinear current-voltage curves are available by cascading two (ITO∕Si)N∕p-GaN films with a bridging Ag film. Furthermore, the current-voltage characteristics can be manipulated by depositing various periods of ITO∕Si multilayers on the p-type GaN substrates. The details of the design principle and the characterizations of the cascading (ITO∕Si)N∕p-GaN thin-film varistors are also discussed.