Efficiency droop behavior improvement through barrier thickness modification for GaN-on-silicon light-emitting diodes

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

doi:10.1117/1.JPE.5.057604

5 March 2015 Efficiency droop behavior improvement through barrier thickness modification for GaN-on-silicon light-emitting diodes

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

Author Affiliations +

Journal of Photonics for Energy, Vol. 5, Issue 1, 057604 (March 2015). https://doi.org/10.1117/1.JPE.5.057604

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 Al_xGa₁−_xN 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.

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An-Jye Tzou, Bing-Cheng Lin, Chia-Yu Lee, Da-Wei Lin, Yu-Kuang Liao, Zhen-Yu Li, Gou-Chung Chi, Hao-Chung Kuo, and Chun-Yen Chang "Efficiency droop behavior improvement through barrier thickness modification for GaN-on-silicon light-emitting diodes," Journal of Photonics for Energy 5(1), 057604 (5 March 2015). https://doi.org/10.1117/1.JPE.5.057604

Published: 5 March 2015

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