標題: | Study of the Excitation Power Dependent Internal Quantum Efficiency in InGaN/GaN LEDs Grown on Patterned Sapphire Substrate |
作者: | Lee, Ya-Ju Chiu, Ching-Hua Ke, Chih Chun Lin, Po Chun Lu, Tien-Chang Kuo, Hao-Chung Wang, Shing-Chung 光電工程學系 Department of Photonics |
關鍵字: | LEDs;GaN;Internal quantum efficiency |
公開日期: | 1-七月-2009 |
摘要: | The mechanisms of the excitation power dependent internal quantum efficiency in InGaN/GaN multiple quantum wells (MQWs) LEDs grown on the planar and the patterned sapphire substrates (PSS) at temperature of 15 and 300 K were investigated. From observation the tendency of emission peak energy and carrier lifetime variation in MQWs with different excitation power for both LED samples, we conclude the internal quantum efficiency would increase as coulomb screening effect dominates at lower carrier injection stage and decrease due to the band-filling effect at higher density stage. At room temperature, the majority of the initial injected carriers would be first consumed by the thermal activated nonradiative centers that hinder the further achievement of high-efficiency LED devices. Experimentally, the internal quantum efficiency of the LED grown on the PSS is similar to 70% and that of the LED grown on the planar sapphire substrate is similar to 62%. For the LED grown on the PSS, the observed higher internal quantum efficiency is due to the larger activation energy Therefore, the reduction of dislocation defects and the prevention of injected carriers escaping from extended states would be a promising prospective for InGaN/GaN MQWs LEDs to achieve high internal quantum efficiency. |
URI: | http://dx.doi.org/10.1109/JSTQE.2009.2014967 http://hdl.handle.net/11536/7056 |
ISSN: | 1077-260X |
DOI: | 10.1109/JSTQE.2009.2014967 |
期刊: | IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS |
Volume: | 15 |
Issue: | 4 |
起始頁: | 1137 |
結束頁: | 1143 |
顯示於類別: | 期刊論文 |