標題: High light-extraction GaN-based vertical LEDs with double diffuse surfaces
作者: Lee, Ya-Ju
Kuo, Hao-Chung
Lu, Tien-Chang
Wang, Shing-Chung
光電工程學系
Department of Photonics
關鍵字: double diffuse surfaces;GaN;light-emitting diodes (LEDs);light-extraction efficiency
公開日期: 1-Nov-2006
摘要: High light-extraction (external quantum efficiency similar to 40%) 465-nm GaN-based vertical light-emitting diodes (LEDs) employing double diffuse surfaces were fabricated. This novel LED structure includes one top transmitted diffuse surface and another diffuse omnidirectional reflector (ODR) on the bottom of a LED chip. The diffusive ODR consists of a roughened p-type GaN layer, an indium-tin-oxide (ITO) low refractive index layer, and an Al layer. The surface of the p-type GaN-layer was naturally roughened while decreasing the growth temperature to 800 degrees C. After flip-bonding onto a Si substrate by AuSn eutectic metal and laser lift-off processes to remove the sapphire substrate, an anisotropic etching by dilute potassium hydroxide (KOH) was employed on the N-face n-GaN layer to obtain transmitted diffuse surfaces with hexagonal-cone morphology. The double diffused surfaces LEDs show an enhancement of 56% and 236% in light output power compared to single side diffused surface and conventional LEDs, respectively. The devices also show a low leakage current in the order of magnitude of 10(-8) A at -5 V and a calculated external quantum efficiency of about 40%. The high scattering efficiency of. double diffused surfaces could be responsible for the enhancement in the device light output power.
URI: http://dx.doi.org/10.1109/JQE.2006.883468
http://hdl.handle.net/11536/11588
ISSN: 0018-9197
DOI: 10.1109/JQE.2006.883468
期刊: IEEE JOURNAL OF QUANTUM ELECTRONICS
Volume: 42
Issue: 11-12
起始頁: 1196
結束頁: 1201
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