Optical and magnetic resonance characterization of undoped and doped wurtzite GaN films deposited on sapphire substrates

Abstract

We have used a combination of defect-sensitive techniques to study native defects and impurities in GaN films deposited on the basal plane of sapphire. The optical and electronic properties of undoped samples are dependent on the degree of compensation between shallow donor and acceptors levels. The paramagnetic studies of undoped films reveal resonances from effective-mass and deep-donor states. Photoluminescence studies of films doped with Mg-acceptors indicate a possible dependence of the localization of the Mg-related center with the increasing concentration of activated acceptors. The optically detected magnetic resonance measurements of Mg-doped samples show that the Mg-acceptor is perturbed from its effective-mass state.