Mechanisms of dislocation reduction in GaN using an intermediate temperature interlayer

A dramatic reduction of the dislocation density in GaN was obtained by inse rtion of a single thin interlayer grown at an intermediate temperature (IT- IL) after the initial growth at high temperature. A description of the grow th process is presented with characterization results aimed at understandin g the mechanisms of reduction in dislocation density. A large percentage of the threading dislocations present in the first GaN epilayer are found to bend near the interlayer and do not propagate into the top layer which grow s at higher temperature in a lateral growth mode. TEM studies show that the mechanisms of dislocation reduction are identical to those described for t he epitaxial lateral overgrowth process, however a notable difference is th e absence of coalescence boundaries.