Correlated structural and optical characterization of ammonothermally grown bulk GaN

A series of ammonothermally grown bulk GaN crystals containing stacking faults has been characterized using structural [transmission electron microscopy (TEM) and synchrotron white-beam x-ray topography (SWBXT)] and optical [low-temperature photoluminescence (PL)] methods. Strong correlations are found between structural and optical properties. In particular, the occurrence of low-temperature PL peaks observed in the 3.30–3.45 eV range correlates with the observation of basal plane stacking faults by TEM (all of which were bounded by Shockley partial dislocations). In addition, the full width at half-maximum of the neutral donor-bound exciton PL peak correlates with the extent of mosaicity revealed on SWBXT Laue patterns recorded from the same crystals.