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

Abstract

We investigate the $3.32 \mathrm{eV}$ 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 $\ensuremath{\approx}$$0.17 \mathrm{eV}$, and are located at the ${I}_{2}$-type basal plane stacking faults.