High thermally stable Ni∕Ag(Al) alloy contacts on p-GaN

Abstract

Ag agglomeration was found to occur at Ni∕Ag to p-GaN contacts after annealing at 500°C. This Ag agglomeration led to the poor thermal stability showed by the Ni∕Ag contacts in relation to the reflectivity and electrical properties. However, after alloying with 10at.% Al by e-gun deposition, the Ni∕Ag(Al) p-GaN contacts were found to effectively retard Ag agglomeration thereby greatly enhancing the thermal stability. Based on the x-ray photoelectron spectroscopy analysis, the authors believe that the key for the retardation of Ag agglomeration was the formation of ternary Al–Ni–O layer at p-GaN interface.