Low resistance Pd/Au ohmic contacts to p-type GaN using surface treatment

Abstract

Ohmic contact to p-type GaN with the lowest contact resistivity was developed by the surface treatment prior to Pd/Au metal deposition. The contact resistivity drastically decreased from 2.9×10−2 to 4.3×10−4 Ω cm2 by the surface treatment using aqua regia. The surface treatment plays a role in removing the surface oxide formed on p-type GaN during epitaxial growth, and subsequently in reducing the barrier height for holes at the interface of Pd/p-type GaN, resulting in the good ohmic contacts to p-type GaN.