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International Journal of Photoenergy
Volume 2012, Article ID 917159, 5 pages
Research Article

Effect of Trapezoidal-Shaped Well on Efficiency Droop in InGaN-Based Double-Heterostructure Light-Emitting Diodes

1Graduate Institute of Electronic Engineering and Green Technology Research Center, Chang Gung University, Taoyuan 333, Taiwan
2MOME, Business Development Group, LED Division, Taoyuan 333, Taiwan

Received 26 July 2011; Revised 8 November 2011; Accepted 16 November 2011

Academic Editor: Carmen Hidalgo

Copyright © 2012 Ray-Ming Lin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We investigated the effects of different well shapes on the external quantum efficiency (EQE) and the efficiency droop in wide-well InGaN/GaN double-heterostructure light-emitting diodes. For forward current densities in the measurement range of greater than 135 A/cm2, the device featuring a trapezoidal well exhibited improved EQEs and alleviative efficiency droop, relative to those of the device featuring a rectangular well. The decreased Auger loss has been proposed as the main reason for the greater maximum efficiency that occurred at high current density (>50 A/cm2). For the devices incorporating trapezoidal and rectangular wells, the EQEs at 200 A/cm2 decreased by 14 and 40%, respectively, from their maximum values, resulting in the EQE at a current density of 200 A/cm2 of the device featuring a trapezoidal well being 17.5% greater than that featuring a rectangular well. These results suggest that, in addition to the decreased Auger loss, the alleviation in efficiency droop at higher current densities might be due to higher internal quantum efficiency resulted from the improved carrier injection efficiency of the trapezoidal well.