Three-Dimensional Atom Probe Characterisation of III-Nitride Quantum Well Structures

Summary

An In_xGa_1−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, was in good agreement with X-ray diffraction measurements. The distribution of indium in the MQWs was analysed: no evidence for either high indium concentration regions or indium clustering was found, in contrast with transmission electron microscopy studies in the literature. We conclude that indium clustering is not necessary for bright luminescence in InGaN.