Finite-element models were developed in order to simulate the stress history during an entire lateral epitaxial overgrowth process: from seed-layer deposition onto a substrate to GaN overgrowth above an SiO2 mask at 1100C and cooling to 20C. Lattice and thermal expansion mismatches between GaN and sapphire were considered simultaneously. Shearing stresses on a series of crystal planes were transiently analyzed. On the basis of the computational results, it was possible to predict the locations of high-density dislocations, and when they developed; as well as the Burgers vectors, dislocation types and directions.

Stress-Based Prediction of Dislocation Generation in GaN during Lateral Epitaxial Overgrowth. Z.Feng, E.Lovell, R.Engelstad, T.Kuech, S.Babcock: Applied Physics Letters, 2002, 80[9], 1547-9