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Optical Engineering

High-performance GaN-based light-emitting diodes on patterned sapphire substrate with a novel hybrid Ag mirror and atomic layer deposition-TiO2/Al2O3 distributed Bragg reflector backside reflector
Author(s): Hao Guo; Hongjun Chen; Xiong Zhang; Peiyuan Zhang; Jianjun Liu; Honggang Liu; Yiping Cui
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Paper Abstract

GaN-based light-emitting diodes (LED) on a patterned sapphire substrate with a novel hybrid atomic layer deposition (ALD)-TiO 2 Al 2 O 3 distributed Bragg reflector (DBR) and Ag mirror have been proposed and fabricated. Due to the excellent thickness uniformity of ALD for the proposed reflector, high reflectivity over 99.3% at an incident angle of 5 deg has been achieved. It was also found that the reflectivity of a backside reflector with an Ag mirror slightly depends on incident light wavelength and incident angle. Moreover, because of the good adhesion between TiO 2 /Al 2 O 3 DBR and the Ag mirror, the fabrication process was simplified and reliable. With a 60 mA current injection, an enhancement of 5.2%, 8.9%, and 47.1% in light output power (LOP) at the 460 nm wavelength was realized for the proposed LED with Ag mirror and 3-pair ALD-TiO 2 Al 2 O 3 DBR as compared with a LED with a traditional Ag mirror and 3-pair TiO 2 /SiO 2 DBR, with Al mirror and 3-pair ALD-TiO 2 Al 2 O 3 DBR, and without backside reflector, respectively. This result shows that the ALD-TiO 2 /Al 2 O 3 DBR can be used to enhance the LOP greatly and improve adhesion between the sapphire substrate and the metallic mirror, and thus is very promising for fabricating high performance GaN-based LEDs.

Paper Details

Date Published: 4 June 2013
PDF: 8 pages
Opt. Eng. 52(6) 063402 doi: 10.1117/1.OE.52.6.063402
Published in: Optical Engineering Volume 52, Issue 6
Show Author Affiliations
Hao Guo, Southeast Univ. (China)
Hongjun Chen, Southeast Univ. (China)
Xiong Zhang, Southeast Univ. (China)
Peiyuan Zhang, Southeast Univ. (China)
Jianjun Liu, Harbin Institute of Technology (China)
Honggang Liu, Institute of Microelectronics (China)
Yiping Cui, Southeast Univ. (China)

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