Ohmic contacts to N-face p-GaN using Ni/Au for the fabrication of polarization inverted light-emitting diodes

Abstract

The electrical properties of Ni-based ohmic contacts to N-face p-type GaN were investigated. The specific contact resistance of N-face p-GaN exhibits a linear decrease from 1.01 Omega cm(2) to 9.05 x 10(-3) Omega cm(2) for the as-deposited and the annealed Ni/Au contacts, respectively, with increasing annealing temperature. However, the specific contact resistance could be decreased down to 1.03 x 10(-4) Omega cm(2) by means of surface treatment using an alcohol-based (NH4)(2)S solution. The depth profile data measured from the intensity of O1s peak in the X-ray photoemission spectra showed That the alcohol-based (NH4)(2)S treatment was effective in removing the surface oxide layer of GaN.