Enhanced performance of vertical GaN-based LEDs with a highly reflective ohmic contact and a nano-roughened indium-zinc oxide transparent conduction layer

Der Ming Kuo, Shui Jinn Wang, Kai Ming Uang, Tron Ming Chen, Wei Chi Lee, Pei Ren Wang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The use of Polystyrene Spheres (PSs) to realize nano-roughened Indium-Zinc Oxide (IZO) surface and a high reflective ohmic p-contact to improve the optoelectronic properties of larger-area (1×1 mm2) vertical metallic-substrate GaN-based light-emitting diodes (VLEDs) were proposed and investigated. A metal system consisting of annealed- Pt/Al/Pt was employed to serve as a reflector and ohmic contact to p-GaN, which exhibits a good ohmic contact (1.84×10-3 Ωcm2) and high reflectivity (88% at 465 nm). After the removal of sapphire using laser lift-off process (LLO) and etching of u-GaN by ICP, Ti/IZO film was then deposited to serve as a transparent conduction layer (TCL). After that, the polystyrene spheres (PSs) were dispersed on the IZO surface, followed by second sputtering-deposition of IZO film to fill the space between neighboring PSs. The PSs were then removed to form a nano-roughened IZO top-layer. Compared to regular VLEDs with Ni/Au ohmic contact and Ti/Al/Ti/Au as reflector layer, the fabricated VLED shows a typical increase in light output power (i.e., ΔLop/Lop) by 72.2% at 350 mA and a decrease in forward voltage (Vf) from 3.43 V down to 3.33 V. It is expected that the proposed PSs nano-roughening technology and high reflection annealed- Pt/Al/Pt metal system for ohmic contact to p-GaN would be a potential candidate for the fabrication of high power GaNbased LEDs for solid-state lighting in the near future.

Original languageEnglish
Title of host publicationLight-Emitting Diodes
Subtitle of host publicationMaterials, Devices, and Applications for Solid State Lighting XIV
DOIs
Publication statusPublished - 2010 May 5
EventLight-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XIV - San Francisco, CA, United States
Duration: 2010 Jan 262010 Jan 28

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume7617
ISSN (Print)0277-786X

Other

OtherLight-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XIV
CountryUnited States
CitySan Francisco, CA
Period10-01-2610-01-28

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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