Investigation of Different Metals as Ohmic Contacts to β-Ga2O3: Comparison and Analysis of Electrical Behavior, Morphology, and Other Physical Properties

Abstract

Nine metals (Ti, In, Ag, Sn, W, Mo, Sc, Zn, and Zr) have been investigated as electrical contacts to n-type single-crystal β-Ga2O3 substrates as a function of annealing temperature up to 800°C (in flowing Ar). For each contact metal, we investigated its electrical behavior and morphology at each annealing temperature, as well as the effects of adding a Au capping layer. Select metals displayed either ohmic (Ti and In) or pseudo-ohmic (Ag, Sn, and Zr) behavior under certain conditions; however, the morphology was often a problem. It was concluded that metal work function is not a dominant factor in forming an ohmic contact to β-Ga2O3 and that limited interfacial reactions play an important role.