High-quality In_0.3Ga_0.7N/GaN quantum well growth and their optical and structural properties

Abstract

We have prepared high-quality In0.3Ga0.7N/GaN quantum wells (QWs) by metallorganic chemical vapour deposition and investigated their optical and structural properties using photoluminescence (PL), high-resolution x-ray diffraction (HRXRD) and cross-section and high-resolution transmission electron microscopy measurements. Growth parameters of the QWs were determined by adjusting the PL peak at around 2.7 eV (460 nm). PL peak intensity increases with the barrier thickness and then saturates and shows maxima when the number of wells is five or six in the In0.3Ga0.7N/GaN QWs. The results of transmission electron microscopy, PL and HRXRD show that the growth rate of the QW and barrier does not change with increasing number of wells in samples grown under optimum growth conditions, i.e. the period (well and barrier) thickness is constant. Based on the measurements of high-resolution transmission electron microscopy and temperature- and excitation-power-dependent PL, the dominant luminescent centre of In0.3Ga0.7N/GaN QWs is a quantum-dot-like localized state.