Three-dimensional atom probe studies of an InxGa1-xN/GaN multiple quantum well structure:: Assessment of possible indium clustering

An InxGa1-xN/GaN multiple quantum well (MQW) structure that exhibited bright photoluminescence was examined with the three-dimensional atom probe. The quantum wells were clearly imaged and the indium fraction x measured to be 0.19 +/- 0.01, in good agreement with x-ray diffraction measurements. The distribution of indium in the MQWs was analyzed: no evidence for either high indium concentration regions or indium clustering was found, in contrast with many of the transmission electron microscopy studies in the literature. The authors conclude that indium clustering is not necessary for bright luminescence in InGaN.