Free-standing wafers (50mm diameter) of GaN were grown by halide vapor phase epitaxy onto lattice-matched γ-LiAlO2. A transmission electron microscopy study of defects and defect densities in the wafers was reported. The growth direction was [10▪0]. Stackingfaults in the basal plane were seen, upon viewing the specimen in the [1¯2▪0] direction, with an average spacing of less than 100nm. Convergent-beam electron diffraction measurements showed no switch in polarity and the faults were therefore proposed to be ABABACAC changes in the stacking. Threading dislocations were found to have a correlated arrangement with a density of 3 x 108/cm2 when viewed in the [1¯2▪0] direction, and widely varying (depending upon location) when viewed in the [00▪1] direction. These dislocations act as seeds for post-growth surface features that directly revealed the correlated nature of these threading dislocations.

Defects in m-Face GaN Films Grown by Halide Vapor Phase Epitaxy on LiAlO2. R.R.Vanfleet, J.A.Simmons, H.P.Maruska, D.W.Hill, M.M.C.Chou, B.H.Chai: Applied Physics Letters, 2003, 83[6], 1139-41