InGaN-based light-emitting diodes fabricated with transparent Ga-doped ZnO as ohmicp-contact

Abstract

Ga-doped ZnO (ZnO: Ga) was fabricated by molecular-beam epitaxy to employ as highly transparent contact electrode on p-GaN layer. ZnO: Ga films have higher transparency in near uv and blue wavelength range than the conventional Ni/Au oxidized alloy p-electrode. The as-deposited ZnO:Ga p-electrodes worked as ohmic contacts for the p-GaN layers without any kind of post annealing processes. The optical power of InGaN light-emitting diode (LED) fabricated with ZnO : Ga p-contact was doubled compared to that with Ni/Au p-electrode. The LED chips with ZnO: Ga were operated at forward current of 20 mA in the environment of temperature of 121 °C, humidity of 85%, and pressure of 1.6 atm. The tested LED has lifetime of 80 and more hours in this environment.