Photoluminescence study on InGaN/GaN quantum well structure grown on (11(2)over-bar-0) sapphire substrate

An investigation of temperature-dependent photoluminescence is carried out on InGaN/GaN multiple-quantum-well (MQW) structures with 2.5 nm well thick- ness grown on (0001) and (11 (2) over bar0) orientation sapphire substrates . Based on a band-tail model. the exciton localization effect is investigat ed with regard to the substrate orientation. On the (0001) sapphire substra te, the emission energy decreases monotonically with increasing temperature from 10 K to room temperature. However, on the (11 (2) over bar0) sapphire substrate, the emission energy shows a temperature-induced blue shift at t emperatures above 70 K, which is a typical characteristic of the occurrence of the exciton localization effect in an InGaN/GaN quantum well structure. Therefore, our result indicates that the exciton localization effect can b e enhanced by growing InGaN/GaN MQW structures on (11 (2) over bar0) sapphi re substrates. Since the exciton localization effect is generally accepted to be advantageous for enhancing the emission quantum efficiency of the InG aN/GaN MQW, the results presented in this paper should be seriously conside red.