Improved External Efficiency InGaN-Based Light-Emitting Diodes with Transparent Conductive Ga-Doped ZnO as p-Electrodes

Ken Nakahara, Kentaro Tamura, Mitsuhiko Sakai, Daisuke Nakagawa, Norikazu Ito, Masayuki Sonobe, Hidemi Takasu, Hitoshi Tampo, Paul Fons, Koji Matsubara, Kakuya Iwata, Akimasa Yamada, Shigeru Niki

Research output: Contribution to journalArticlepeer-review

63 Citations (Scopus)

Abstract

Transparent conductive Ga-doped ZnO (ZnO:Ga) was fabricated to serve as p-contacts of InGaN-based light-emitting diodes (LEDs) using molecular-beam epitaxy. As-grown ZnO:Ga films typically have resistivities of ρ = 2 - 4 × 10-4 Ω-cm, and over 80% transparency in the near UV and visible wavelength ranges. The current-voltage characteristics between as-grown ZnO:Ga contacts and p-GaN layers were ohmic. The brightness of LEDs fabricated with ZnO:Ga p-contacts was nearly double compared to LEDs with conventional Ni/Au p-contacts. We obtained the external efficiency as high as 20.8% in the case of the near UV LED. The forward voltage at 20mA was found not to increase even after the lamp LED with ZnO:Ga were kept for 80h in high humidity and high temperature environments.

Original languageEnglish
Pages (from-to)L180-L182
JournalJapanese Journal of Applied Physics, Part 2: Letters
Volume43
Issue number2 A
DOIs
Publication statusPublished - 2004 Feb 1

Keywords

  • External efficiency
  • GaN
  • InGaN
  • LED
  • MBE
  • Ohmic contact
  • Reliability
  • Transparent
  • ZnO

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy (miscellaneous)
  • Physics and Astronomy(all)

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