The role of Mg was studied in the formation of basal stacking faults and a phase transition in InxGa1-xN layers doped with Mg grown by molecular beam epitaxy on Si (111) substrates with AlN buffer layers. Several samples with varying In content between x ~0.1 and x ~0.3 were examined by transmission electron microscopy and other techniques. High densities of basal stacking faults were observed in the central region of the InGaN layer away from the substrate or layer surface, but at varying depths within this region. Selected area diffraction patterns showed that while the InGaN layer was initially in the wurtzite phase (and of good quality) AlN buffer layer, there was a change to the zincblende phase in the upper part of the InGaN layer. SIMS measurements showed that the Mg concentration fell from a maximum to a steady concentration coinciding with the presence of the basal stacking faults. There was little change in In or Ga concentrations in the same area. High-resolution electron microscopy from the area of the stacking faults confirmed that the change to the cubic phase was abrupt across one such fault. These results indicated that Mg played  a role in the formation of stacking faults and the phase change observed in InxGa1-xN alloys.

Stacking Faults and Phase Changes in Mg-Doped InGaN Grown on Si. M.E.Hawkridge, Z.Liliental-Weber, K.M.Yu, L.A.Reichertz, W.J.Schaff, J.W.Ager, W.Walukiewicz: Physica Status Solidi C, 2009, 6[S2], S421-4