I2basal plane stacking fault in GaN: Origin of the 3.32 eV luminescence band

Abstract

We investigate the $3.32\hspace{0.5em}\mathrm{eV}$ defect-related emission band in GaN correlating transmission electron microscopy and spatially and spectrally resolved cathodoluminescence at low temperature. The band is unambiguously associated with basal plane stacking faults of type $I_2$, which are a common defect type in semi- and nonpolar GaN grown on foreign substrates. We ascribe the luminescence to free-to-bound transitions. The suggested intrinsic acceptors involved have an ionization energy of $\approx$ $0.17\hspace{0.5em}\mathrm{eV}$, and are located at the $I_2$-type basal plane stacking faults.