標題: The effect of free-standing GaN substrate on carrier localization in ultraviolet InGaN light-emitting diodes
作者: Tsai, Ming-Ta
Chu, Chung-Ming
Huang, Che-Hsuan
Wu, Yin-Hao
Chiu, Ching-Hsueh
Li, Zhen-Yu
Tu, Po-Min
Lee, Wei-I
Kuo, Hao-Chung
電子物理學系
光電工程學系
Department of Electrophysics
Department of Photonics
關鍵字: Ultraviolet;Light-emitting diodes;Homoepitaxially;Carrier confinement;External quantum efficiency
公開日期: 13-十二月-2014
摘要: In this study, we have grown 380-nm ultraviolet light-emitting diodes (UV-LEDs) based on InGaN/AlInGaN multiple quantum well (MQW) structures on free-standing GaN (FS-GaN) substrate by atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD), and investigated the relationship between carrier localization degree and FS-GaN. The micro-Raman shift peak mapping image shows low standard deviation (STD), indicating that the UV-LED epi-wafer of low curvature and MQWs of weak quantum-confined Stark effect (QCSE) were grown. High-resolution X-ray diffraction (HRXRD) analyses demonstrated high-order satellite peaks and clear fringes between them for the UV-LEDs grown on the FS-GaN substrate, from which the interface roughness (IRN) was estimated. The temperature-dependent photoluminescence (PL) measurement confirmed that the UV-LEDs grown on the FS-GaN substrate exhibited better carrier confinement. Besides, the high-resolution transmission electron microscopy (HRTEM) and energy-dispersive spectrometer (EDS) mapping images verified that the UV-LEDs on FS-GaN have fairly uniform distribution of indium and more ordered InGaN/AlInGaN MQW structure. Clearly, the FS-GaN can not only improve the light output power but also reduce the efficiency droop phenomenon at high injection current. Based on the results mentioned above, the FS-GaN can offer UV-LEDs based on InGaN/AlInGaN MQW structures with benefits, such as high crystal quality and small carrier localization degree, compared with the UV-LEDs on sapphire.
URI: http://dx.doi.org/10.1186/1556-276X-9-675
http://hdl.handle.net/11536/124258
ISSN: 1556-276X
DOI: 10.1186/1556-276X-9-675
期刊: NANOSCALE RESEARCH LETTERS
顯示於類別:期刊論文


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