Highly reliable Ag/Zn/Ag ohmic reflector for high-power GaN-based vertical light-emitting diode

Opt Express. 2012 Aug 13;20(17):19194-9. doi: 10.1364/OE.20.019194.

Abstract

We report the improved performance of InGaN/GaN-based light-emitting diodes (LEDs) through Ag reflectors combined with a Zn middle layer. It is shown that the Zn middle layer (5 nm thick) suppresses the agglomeration of Ag reflectors by forming ZnO and dissolving into Ag. The Ag/Zn/Ag contacts show a specific contact resistance of 6.2 × 10(-5) Ωcm(2) and reflectance of ~83% at a wavelength of 440 nm when annealed at 500 °C, which are much better than those of Ag only contacts. Blue LEDs fabricated with the 500 °C-annealed Ag/Zn/Ag reflectors show a forward voltage of 2.98 V at an injection current of 20 mA, which is lower than that (3.02 V) of LEDs with the annealed Ag only contacts. LEDs with the 500 °C-annealed Ag/Zn/Ag contacts exhibit 34% higher output power (at 20 mA) than LEDs with the annealed Ag only contacts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Electric Impedance
  • Equipment Design
  • Equipment Failure Analysis
  • Gallium / chemistry*
  • Lenses*
  • Lighting / instrumentation*
  • Pattern Recognition, Automated / methods*
  • Semiconductors*
  • Silver / chemistry*
  • Zinc / chemistry*

Substances

  • gallium nitride
  • Silver
  • Gallium
  • Zinc