Enhanced carrier localization in near-ultraviolet multiple quantum wells using quaternary AlInGaN as the well layers

Abstract

The structural and optical properties of near-ultraviolet (UV) multiple quantum well (MQW) structures using quaternary AlInGaN as the well layers have been investigated. The composition of the barrier layers is determined by three In_0.08Ga_0.92N/Al_xIn_yGa_1−x−yN multiple quantum well samples with varying Al content in the barrier layers. The compositions of the well and barrier layers are estimated from the high-resolution X-ray diffraction (HRXRD) results. In spite of the larger lattice mismatch, the remarkable enhancement of the photoluminescence (PL) intensity of the MQWs sample with AlInGaN as the well layers is attributed to the increase in the carrier localized states induced by the increase in the compositional fluctuation in the AlInGaN well layers. The S-shaped temperature-dependence of the PL peak energy indicates the existence of localized states induced by the potential fluctuations. The magnitude of the carrier localization, which is estimated by the fitting results, is significantly increased in the Al_0.11In_0.13Ga_0.76N/Al_0.16In_0.045Ga_0.795N MQWs due to the improvement of the spatial potential fluctuations using quaternary AlInGaN as the well layers.