Transmission electron microscopy and optical characterization of GaN dots, embedded in an AlN matrix, was carried out. The dots were grown, by means of molecular beam epitaxy, on top of an AlN layer which had been deposited onto (00•1) sapphire. It was found that the dots, with an average diameter of 16nm and an average height of 4nm, were coherently grown on AlN, but nucleated next to threading edge dislocations that were propagating in AlN. The presence of these adjacent dislocations did not inhibit the optical emission of the dots. Unlike the photoluminescence from thick GaN layers or GaN/AlGaN quantum wells, the photoluminescence of the GaN dots was found to be temperature-independent.

Preferential Nucleation of GaN Quantum Dots at the Edge of AlN Threading Dislocations. J.L.Rouvière, J.Simon, N.Pelekanos, B.Daudin, G.Feuillet: Applied Physics Letters, 1999, 75[17], 2632-4