Hydrogen peroxide treatment induced rectifying behavior of Au/n-ZnO contact

Conversion of the Au/n-ZnO contact from Ohmic to rectifying with H2O2 pretreatment was studied systematically using I-V measurements, x-ray photoemission spectroscopy, positron annihilation spectroscopy, and deep level transient spectroscopy. H2O2 treatment did not affect the carbon surface contamination or the E-C-0.31 eV deep level, but it resulted in a significant decrease of the surface OH contamination and the formation of vacancy-type defects (Zn vacancy or vacancy cluster) close to the surface. The formation of a rectifying contact can be attributed to the reduced conductivity of the surface region due to the removal of OH and the formation of vacancy-type defects. (c) 2007 American Institute of Physics.