An investigation was made of the conditions which gave rise to the surface reconstruction of GaN which was grown, by molecular beam epitaxy, onto (00•¯1) bulk GaN substrates. The results of various surface reconstructions were investigated by supplying Ga and active N separately to GaN surfaces. A (2 x 2) reconstruction on (00•¯1)GaN substrates, and on GaN layers grown on such substrates, was observed. The (2 x 2) surface reconstruction was stable in the presence of an active N flux at high temperatures, but it disappeared upon cooling the GaN sample to below about 400C. The (2 x 2) reconstruction was considered to be due to an additional amount of relatively tightly bound Ga on this (1 x 1) surface. Adding further Ga to the (2 x 2) reconstructed surface resulted in a return to a (1 x 1) reconstruction.

Surface Reconstruction Patterns of GaN Grown by Molecular Beam Epitaxy on GaN Bulk Crystals C.T.Foxon, T.S.Cheng, S.V.Novikov, D.Korakakis, N.J.Jeffs, I.Grzegory, S.Porowski: Journal of Crystal Growth, 1999, 207[1-2], 1-7