The effects of oxygen contamination on the properties of reactively sputtered indium nitride films

Abstract

Thin films of InN, a direct band gap semiconductor, were deposited by dc planar magnetron sputtering of an indium target in a pure nitrogen atmosphere. Rutherford backscattering analysis of the film stoichiometry showed oxygen contamination of at least 11 at. % throughout the film thickness. In spite of this bulk contamination, the crystal structure showed no evidence of In2O3 or of an indium oxynitride. The band gap also was indicative of InN (1.89 eV), not In2O3 (3.6 eV). We propose that the oxygen forms an amorphous indium oxynitride that exists in an InN polycrystalline matrix, and that this amorphous oxynitride decreases the electron mobility of the films.