Optical and Magnetic Resonance Studies of Mg-Doped GaN Homoepitaxial Layers Grown by Molecular Beam Epitaxy.

摘要

Low-temperature photoluminescence (PL) and optically detected magnetic resonance (ODMR) at 24GHz have been performed on a series of MBE-grown Mg-doped (10 expn 17)-10 expn (20)cm expn -(3) GaN homoepitaxial layers. High- resolution PL at 5K revealed intense bandedge emission with narrow linewidths (0.2-0.4 meV) attributed to annihilation of excitons bound to shallow Mg acceptors. In contrast to many previous reports for GaN heteroepitaxial layers doped with Mg> 10(expn 18) cm(expn -3), the only visible PL observed was strong shallow donor/shallow acceptor recombination with zero phonon line at 3.27 eV. Most notably, ODMR on this emission from a sample doped with Mg of 1 x 10(expn 17)cm(expn -3) revealed the first evidence for the highly anisotropic g-tensor (g sub parallel) approximately (2.19, g sub perpendicular) approximately (0) expected for Mg shallow acceptors in wurtzite GaN. This result is attributed to the much reduced dislocation densities.