Electrical and thermal stability of Ag ohmic contacts for GaN-based flip-chip light-emitting diodes by using an AgAl alloy capping layer

Yoon Tae Hwang, Hyun Gi Hong, Tae Yeon Seong, D. S. Leem, T. Lee, K. K. Kim, J. O. Song

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

We have investigated Ag(200 nm)/AgAl(100 nm) ohmic contacts to p-type GaN for near-UV (405 nm) flip-chip light-emitting diodes (LEDs). It is shown that the use of an AgAl alloy capping layer (with 8 at% Al) results in better electrical and optical properties as compared to single Ag contacts when annealed at 430 °C. For example, Ag/AgAl (8 at% Al) contacts give specific contact resistance of 4.6×10-4 Ω cm2 and reflectance of 90% at a wavelength of 405 nm. However, use of an AgAl (with 50 at% Al) layer is not effective. LEDs fabricated with the Ag/AgAl (8 at% Al) reflectors produce higher light output as compared with the ones with single Ag reflectors. Ohmic mechanisms of the Ag/AgAl (8 at% Al) contacts are described and discussed.

Original languageEnglish
Pages (from-to)14-18
Number of pages5
JournalMaterials Science in Semiconductor Processing
Volume10
Issue number1
DOIs
Publication statusPublished - 2007 Feb

Keywords

  • Ag reflector
  • AgAl capping layer
  • GaN-based flip-chip LEDs
  • Ohmic contacts
  • Thermal stability

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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