Significant internal quantum efficiency (IQE) enhancement of GaN/AlGaN multiple quantum wells (MQWs) emitting at similar to 350 nm was achieved via a step quantum well (QW) structure design. The MQW structures were grown on AlGaN/AlN/sapphire templates by metal-organic chemical vapor deposition (MOCVD). High resolution x-ray diffraction (HR-XRD) and scanning transmission electron microscopy (STEM) were performed, showing sharp interface of the MQWs. Weak beam dark field imaging was conducted, indicating a similar dislocation density of the investigated MQWs samples. The IQE of GaN/AlGaN MQWs was estimated by temperature dependent photoluminescence (TDPL). An IQE enhancement of about two times was observed for the GaN/AlGaN step QW structure, compared with conventional QW structure. Based on the theoretical calculation, this IQE enhancement was attributed to the suppressed polarization-induced field, and thus the improved electron-hole wave-function overlap in the step QW.
|Original language||English (US)|
|Journal||Journal of Physics D: Applied Physics|
|State||Published - May 3 2017|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): BAS/1/1664/01-01
Acknowledgements: This work was supported by KAUST Startup and Baseline Funds (Grant No. BAS/1/1664/01-01); National Key R&D Program of China (Grant No. 2016YFB0400901, 2016YFB0400804); National Basic Research Program of China (Grant No. 2012CB619302); Key Laboratory of infrared imaging materials and detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences (Grant No. IIMDKFJJ-15-07); National Natural Science Foundation of China (Grant No. 61675079, 11574166, 61377034), and the Director Fund of WNLO.