Influences of excitation power and temperature on photoluminescence in phase-separated InGaN quantum wells**Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120131110006), the Key Science and Technology Program of Shandong Province, China (Grant No. 2013GGX10221), the Key Laboratory of Functional Crystal Materials and Device (Shandong University, Ministry of Education) (Grant No.

Abstract

The photoluminescence (PL) properties of a green and blue light-emitting InGaN/GaN multiple quantum well structure with a strong phase separated into quasi-quantum dots (QDs) and an InGaN matrix in the InGaN epilayer are investigated. The excitation power dependences of QD-related green emissions (PD) and matrix-related blue emissions (PM) in the low excitation power range of the PL peak energy and line-width indicate that at 6 K both PM and PD are dominated by the combined action of Coulomb screening and localized state filling effect. However, at 300 K, PM is dominated by the non-radiative recombination of the carriers in the InGaN matrix, while PD is influenced by the carriers transferred from the shallower QDs to deeper QDs by tunnelling. This is consistent with the excitation power dependence of the PL efficiency for the emission.