It was noted that the quality of hetero-epitaxial material could be significantly improved if threading dislocations, originating from the interface, were prevented from reaching the layer surface; where they could propagate to active areas and act as harmful defects. Incorporation of an intermediate layer which was grown at low temperatures was known to limit such defect propagation. This method was effective, but several interlayers were usually required in order to depress the dislocation density to below 109/cm2. In the present work, high-quality layers were grown by using only one intermediate layer. The dislocation density here was only 8 x 107/cm2; as compared to over 1010/cm2 for layers which were grown without an intermediate layer.

Study of High-Quality GaN Grown by OMVPE using an Intermediate Layer. M.Benamara, Z.Liliental-Weber, S.Kellermann, W.Swider, J.Washburn, J.Mazur, E.D.Bourret-Courchesne: Journal of Crystal Growth, 2000, 218[2-4], 447-50