Correlated structural and optical characterization of ammonothermally grown bulk GaN

Structural [transmission electron microscopy (TEM) and synchrotron white-beam x-ray topography (SWBXT)] and optical [low temperature photoluminescence (PL)] methods were used to investigate a series of ammonothermally grown bulk GaN crystals containing stacking faults. TEM show that occurrence of low-temperature PL peaks observed in the 3.30-3.45 eV rage correlates with the observation of basal plane stacking faults (BPSF). This supports the association of PL peaks with quantum-well regions. The results shows that with the ammonothermal growth technique, it is possible to produce high quality millimeter-sized crystals with low structural defect density and high optical quality.