Stacking faults and phase changes in Mg‐doped InGaN grown on Si

Abstract

AbstractWe report evidence for the role of Mg 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 are examined by transmission electron microscopy and other techniques. High densities of basal stacking faults are 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 show that while the InGaN layer is initially in the wurtzite phase (and of good quality) AlN buffer layer, there is a change to the zinc blende phase in the upper part of the InGaN layer. SIMS measurements show that the Mg concentration drops from a maximum to a steady concentration coinciding with the presence of the basal stacking faults. There is little change in In or Ga concentrations in the same area. High‐resolution electron microscopy from the area of the stacking faults confirms that the change to the cubic phase is abrupt across one such fault. These results indicate that Mg plays a role in the formation of stacking faults and the phase change observed in InxGa1‐xN alloys. We also consider the role of In in the formation of these defects. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)