The mechanism of blueshift in excitation-intensity-dependent photoluminescence spectrum of nitride multiple quantum wells

(1 1 2̄ 0) GaN/InGaN multiple quantum wells (MQWs) were grown on (1 1̄ 0 2) sapphire by metal-organic vapor phase epitaxy. The excitation-intensity-dependent photoluminescence (PL) spectrum of these samples was measured, and no peak shift was observed. This phenomenon was attributed to the absence of piezoelectric field (PEF) along the growth orientation of the (1 1 2̄ 0) face MQWs. Our experimental results showed that PEF was the main reason causing peak blueshift in excitation-intensity-dependent PL spectrum of (0 0 0 1) InGaN/GaN MQWs. It was expected that fabricating (1 1 2̄ 0) face nitride device should be a method to avoid PEF and get low-threshold, high-quantum-efficiency and stable-emission-wavelength light-emission devices.