Investigation on the origin of wurtzite domains in thick cubic GaN using reactive ion etching

We measured the depth profiling of photoluminescence (PL) in cubic GaN film s. The depth-resolved PL of normal grown GaN layers showed that the near-ba nd-edge luminescence intensities of both cubic and wurtzite domains remaine d constant only until an etching depth of up to 2.7 mu m, but their ratio r emained unchanged at all etching depths. Moreover, when a thin In0.1Ga0.9N layer was sandwiched between two GaN layers, the content of the wurtzite do mains increased, and its distribution showed a dependence on thickness. As the reactive ion etching depth increased, the PL intensity ratio of cubic G aN to wurtzite domains increased. Based on the distribution, the strain rel axation, instead of the instability of cubic GaN at high temperature, was a ttributed to the origin of wurtzite domains. (C) 2000 Elsevier Science S.A. All rights reserved.