Unambiguously enhanced ultraviolet luminescence of AlGaN wavy quantum well structures grown on large misoriented sapphire substrate

by Haiding Sun, Somak Mitra, Ram Chandra Subedi, Yi Zhang, Wei Guo, Jichun Ye, Mohammad Khaled Shakfa, Tien Khee Ng, Boon S Ooi, Iman S Roqan, Zihui Zhang, Jiangnan Dai, Changqing Chen, Shibing Long
Year: 2019

Abstract

High‐quality epitaxy consisting of Al1−xGaxN/Al1−yGayN multiple quantum wells (MQWs) with sharp interfaces and emitting at ≈280 nm is successfully grown on sapphire with a misorientation angle as large as 4°. Wavy MQWs are observed due to step bunching formed at the step edges. A thicker QW width accompanied by a greater accumulation of gallium near the macrostep edge than that on the flat‐terrace is observed on 4° misoriented sapphire, leading to the generation of potential minima with respect to their neighboring QWs. Consequently, a significantly enhanced photoluminescence intensity (at least ten times higher), improved internal quantum efficiency (six times higher at low excitation laser power), and a much longer carrier lifetime are achieved. Importantly, the wafer‐level output‐power of the ultraviolet light emitting diodes on 4° misoriented substrate is nearly increased by 2–3 times. This gain is …

Keywords

Unambiguously Enhanced Ultraviolet Luminescence of AlGaN Wavy Quantum Well Structures Grown on Large Misoriented Sapphire Substrate