Photoluminescence Excitation Spectroscopy of InxGa1–xN/GaN Multiple Quantum Wells with Various In Compositions

Luminescence properties of In x Ga 1-x N/GaN multiple quantum wells (MQWs) with various In compositions have been studied by means of photoluminescence excitation (PLE) spectroscopy. The clear peak due to the absorption of In x Ga 1-x N quantum wells was observed in the PLE spectrum of the MQW sample with x < 0.01 at 4 K, and the Stokes shift was estimated to be 63 meV. It was found from temperature-dependent PLE measurements that the Stokes shift was independent of temperature up to 300 K. This result suggests that the large Stokes shift cannot be explained only by the effect of carrier localization due to compositional fluctuation.