Ion irradiation of inhomogeneous Schottky barriers on silicon carbide

Abstract

In this paper, the effects of ion irradiation on Schottky barriers formed on silicon carbide are discussed. After Si-ion irradiation at the near-interface region in Ti/4H-SiC contacts an increase of the Schottky barrier height from 1.05 to 1.21 eV was observed, accompanied by a lowering of the reverse leakage current. The combination of several methods allowed us to determine the physical properties of the Schottky barrier and to explain the mechanism responsible for the barrier height changes. In particular, the structural and electrical modifications of the interfacial region, both of Ti layer and SiC (i.e., different orientation of the Ti layer, irradiation-induced defects in the epilayer, dopant deactivation, and the consequent reduction of the surface electric field) are responsible for the increase of the Schottky barrier height and the reduction of the leakage current. The electrical characterization of the contacts at different temperatures also suggested that ion irradiation induced modifications in the inhomogeneous nature of the Ti Schottky barrier.