Hydrogen-related local vibrational modes in GaN:Mg grown by molecular beam epitaxy

Abstract

ABSTRACTWe report a Raman scattering study of local vibrational modes (LVMs) on Mg-doped GaN grown by molecular beam epitaxy (MBE). Besides Mg:Ga local vibrational modes clearly observed at 262 and 565 cm−1, several peaks were detected in the spectral regions around 2200 cm−1 and 2900 cm−1. The modes in the 2200 cm−1 spectral region correspond to local modes of hydrogen complexes and hydrogen-decorated defects, and indicate the presence of a fairly high concentration of H in the samples. The peaks observed in the 2900 cm−1 region are assigned to carbon-hydrogen local modes and are indicative of the presence of C impurities in the samples. These measurements show that both C and H impurities may be present in sizable amounts not only in metal-organic chemical vapor deposition (MOCVD) samples but also in MBE grown samples, and this may have an effect on the electrical conductivity ofp-type GaN:Mg samples.