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Journal of Photonics for Energy

Efficiency droop behavior improvement through barrier thickness modification for GaN-on-silicon light-emitting diodes
Author(s): An-Jye Tzou; Bing-Cheng Lin; Chia-Yu Lee; Da-Wei Lin; Yu-Kuang Liao; Zhen-Yu Li; Gou-Chung Chi; Hao-Chung Kuo; Chun-Yen Chang
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Paper Abstract

Crack-free GaN-based light-emitting diodes (LEDs) were grown on 150-mm-diameter Si substrates by using low-pressure metal-organic chemical vapor deposition. The relationship between the LED devices and the thickness of quantum barriers (QBs) was investigated. The crystal quality and surface cracking of GaN-on-Si were greatly improved by an AlxGa1xN buffer layer composed of graded Al. The threading dislocation density of the GaN-on-Si LEDs was reduced to <7×108  cm−2, yielding LEDs with high internal quantum efficiency. Simulation results indicated that reducing the QB thickness improved the carrier injection rate and distribution, thereby improving the droop behavior of the LEDs. LEDs featuring 6-nm-thick QBs exhibited the lowest droop behavior. However, the experimental results showed an unanticipated phenomenon, namely that the peak external quantum efficiency (EQE) and light output power (LOP) gradually decreased with a decreasing QB thickness. In other words, the GaN-on-Si LEDs with 8-nm-thick QBs exhibited low droop behavior and yielded a good peak EQE and LOP, achieving a 22.9% efficiency droop and 54.6% EQE.

Paper Details

Date Published: 5 March 2015
PDF: 14 pages
J. Photon. Energy 5(1) 057604 doi: 10.1117/1.JPE.5.057604
Published in: Journal of Photonics for Energy Volume 5, Issue 1
Show Author Affiliations
An-Jye Tzou, National Chiao Tung Univ. (Taiwan)
Bing-Cheng Lin, National Chiao Tung Univ. (Taiwan)
Chia-Yu Lee, National Chiao Tung Univ. (Taiwan)
Da-Wei Lin, National Chiao Tung Univ. (Taiwan)
Yu-Kuang Liao, National Chiao Tung Univ. (Taiwan)
Zhen-Yu Li, National Chiao Tung Univ. (Taiwan)
Research Center for Applied Sciences (Taiwan)
Gou-Chung Chi, National Chiao Tung Univ. (Taiwan)
Hao-Chung Kuo, National Chiao Tung Univ. (Taiwan)
Chun-Yen Chang, National Chiao Tung Univ. (Taiwan)
Academia Sinica (Taiwan)

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