Highly reflective and low-resistant Ni/Au/ITO/Ag ohmic contact on p-type GaN

Abstract

We report low-resistant and high reflective ohmic contact on p-type GaN using a promising Ni/Au/indium-tin oxide (ITO)/Ag contact scheme. Specific contact resistivity as low as 3.2x10(-5) Omega cm(2) was obtained from Ni(20Angstrom)/Au (30Angstrom)/ITO (600 Angstrom)/Ag (1200 Angstrom) contact annealed at 500degreesC under an oxidizing ambient. The relative reflectance of contact was evaluated to be 78.8%, which is 14.6% higher than the Ni/Au contact. The ITO layer acted as a diffusion barrier for both indiffusion of Ag and out-diffusion of Au, providing a low resistant and highly reflective ohmic contact on p-type GaN. (C) 2004 The Electrochemical Society.