Electron Spin Resonance in GaN Thin Film Doped with Fe

Abstract

High-quality and high-resistivity semiconducting substrates are needed to fabricate high-frequency devices such as high-mobility transistors based on gallium nitride (GaN). A GaN thin film doped with Fe ions becomes one of such high-resistivity substrates. To obtain microscopic information on the Fe ions in the GaN:Fe film, we have performed electron spin resonance (ESR) measurements using a conventional X-band apparatus and home made Q-band equipment. The observed ESR signals were analyzed with a spin Hamiltonian given by considering the local symmetry of the Ga site (C3v) and assuming that the Fe3+ ions (S=5/2) are substituted for Ga3+ ions. As a result, the angular dependence of the resonance fields and the temperature dependence of the signal intensities are reproduced very well by the calculations. Consequently, we confirmed that the Fe3+ ions occupy some of the Ga sites in the GaN thin film.