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International Journal of Photoenergy
Volume 2015, Article ID 135321, 6 pages
http://dx.doi.org/10.1155/2015/135321
Research Article

Investigating the Effect of Piezoelectric Polarization on GaN-Based LEDs with Different Prestrain Layer by Temperature-Dependent Electroluminescence

1Department of Electronic Engineering, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan
2Epistar Corporation, Tainan 744, Taiwan

Received 24 July 2014; Revised 11 September 2014; Accepted 16 September 2014

Academic Editor: Sheng-Po Chang

Copyright © 2015 C. K. Wang 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.

Abstract

The effect of piezoelectric polarization on GaN-based light emitting diodes (LEDs) with different kinds of prestrain layers between the multiple quantum wells (MQWs) and n-GaN layer is studied and demonstrated. Compared with the conventional LED, more than 10% enhancement in the output power of the LED with prestrain layer can be attributed to the reduction of polarization field within MQWs region. In this study, we reported a simple method to provide useful comparison of polarization fields within active region in GaN-based LEDs by using temperature-dependent electroluminescence (EL) measurement. The results pointed out that the polarization field of conventional LED was stronger than that of the others due to larger variation of the wavelength transition position (i.e., blue-shift change to red-shift) from 300 to 350 K, and thus the larger polarization field must be effectively screened by injecting more carriers into the MQWs region.