A method for reducing the dislocation density in thin films, via lateral overgrowth from trenches, was described. In this process, a thin nitride film was first grown onto a sapphire substrate. Trenches were then formed in the film by etching. The nitride was subsequently re-grown laterally from the trench side-walls so as to form a continuous thin film. The average surface density of threading dislocations was reduced, from 8 x 109/cm2 in the first thin film, to 6 x 107/cm2 in the re-grown thin film.

Dislocation Reduction in GaN Thin Films via Lateral Overgrowth from Trenches Y.Chen, R.Schneider, S.Y.Wang, R.S.Kern, C.H.Chen, C.P.Kuo: Applied Physics Letters, 1999, 75[14], 2062-3