Photoluminescence investigation of In0.15Ga0.85N/GaN multiple quantum wells

The photoluminescence (PL) spectra of InGaN/GaN multiple quantum wells (MQWs) grown by using metalorganic chemical vapor deposition were investigated by varying the PL temperature and the excitation power density. The PL spectrum of InGaN/GaN MQWs exhibits a multi-like feature related to the InGaN well at low temperature, indicating a nonuniformity of the indium composition due to the miscibility between InN and GaN, which results in an exciton localization effect. With increasing excitation power density, the emission peak of the MQW exhibits a blueshift and its linewidth decreases. Based on the theory of the quantum confined Stark effect, the behavior of the MQW can be well explained. The high-energy emission is quenched quickly by increasing temperature, and the low-energy emission becomes dominant because of the different activation energy, which proves that the high-energy emission is a MQW-related emission and that the lowenergy emission is from strongly localized excitons.