Spectroscopic signatures of native charge compensation in Mg doped GaN nanorods

Abstract

We study the native charge compensation effect in Mg doped GaN nanorods (NRs), grown by Plasma Assisted Molecular Beam Epitaxy (PAMBE), using Raman, photoluminescence (PL) and x-ray photoelectron spectroscopies (XPS). The XPS valence band analysis shows that upon Mg incorporation the EF − EVBM reduces, suggesting the compensation of the native n-type character of GaN NRs. Raman spectroscopic studies of these samples reveal that the line shape of the longitudinal phonon plasmon (LPP) coupled mode is sensitive to Mg concentration and hence to the background n-type carrier density. We estimate a two order of native charge compensation in GaN NRs upon Mg-doping with a concentration of 1019–1020 atoms cm−3. The atomistic origin of this compensation effect in these GaN nanorod samples is discussed.