A comparative study was made of the defect microstructures of various regions in epitaxial monocrystalline GaN structures which had been grown under differing conditions. The defects in GaN which had been grown within SiO2 windows were predominantly threading dislocations of mainly mixed character, with a Burgers vector of 1/3<11•3> and edge dislocations with 1/3<11•0>; at densities ranging from 109 to 1010/cm2. Regions of lateral epitaxial overgrowth contained short dislocation segments which were parallel to interfacial planes which, in turn, were usually aligned parallel to the <1¯1•0> or <11•0> directions. They had densities of less than 106/cm2. The morphologies which were exhibited by lateral epitaxial overgrowth samples were associated with stress relaxation.

Lateral Epitaxy and Dislocation Density Reduction in Selectively Grown GaN Structures. T.S.Zheleva, O.H.Nam, W.M.Ashmawi, J.D.Griffin, R.F.Davis: Journal of Crystal Growth, 2001, 222[4], 706-18