Photoluminescence properties of InGaN/GaN multiple quantum wells containing a gradually changing amount of indium in each InGaN well layer along the growth direction

Temperature dependences of photoluminescence (PL) spectra of two different InGaN/GaN multiple quantum wells (MQWs) were studied at different excitation powers. The results show that, compared with MQWs with a gradually increased In content, the MQWs with a gradually decreased In content showed a lower peak energy, stronger phase separation, more robust carrier localization effect, and a stronger quantum-confined Stark effect (QCSE). These characteristics are attributed to a fact that, compared with the former, the latter has a higher average In content in the layer of each InGaN well, due to the less significant volatilization of In incorporated therein. •PL properties of two different InGaN/GaN MQW samples A and B were studied.•Sample A (B) was deposited by gradually increasing (decreasing) TMIn flow rate.•Sample B shows a lower peak energy, and a stronger localization effect and QCSE.•These characteristics are attributed to a higher average In content in sample B.•The higher In content in sample B is due to its less significant In volatilization.