Non-alloyed Cr/Au Ohmic contacts to N-face and Ga-face n-GaN

Abstract

Non-alloyed Cr/Au Ohmic contacts on N-face and Ga-face n-GaN were studied. The specific contact resistances (rho(c)) of Cr/Au contacts onto the N-face and Ga-face n-GaN were as low as 2.4 x 10 (4) Omega cm(2) and 2.4 x 10(-5) Omega cm(2), respectively. Native oxide formed on the n-GaN surface was believed to be the key factor for higher rho(c). The results of X-ray photoelectron spectroscopy confirmed that n-GaN samples with different surface polarities or treated by different chemical solutions exhibited significant differences in gallium oxide content on the surface, which led to a marked difference in the rho(c) of non-alloyed Cr/Au Ohmic contacts to GaN films. (C) 2011 Elsevier B.V. All rights reserved.