A dramatic reduction of the dislocation density in GaN was obtained by insertion of a single thin interlayer grown at an intermediate temperature after initial growth at high temperatures. A description of the growth process was presented with characterization results aimed at understanding the mechanisms of reduction in dislocation density. A large percentage of the threading dislocations present in the first GaN epilayer were found to bend near to the interlayer and did not propagate into the top layer which grows at higher temperature in a lateral growth mode. Transmission electron microscopic studies showed that the mechanisms of dislocation reduction were identical to those described for the epitaxial lateral overgrowth process, however a notable difference was the absence of coalescence boundaries.

Mechanisms of Dislocation Reduction in GaN Using an Intermediate Temperature Interlayer. E.D.Bourret-Courchesne, K.M.Yu, M.Benamara, Z.Liliental-Weber, J.Washburn: Journal of Electronic Materials, 2001, 30[11], 1417-20