Au/N-type Si Schottky-barrier contact and oxidation kinetics in Au-contaminated and thermally oxidized N-type Si (001) surfaces

Abstract

Anomalous Au locations in SiO2/Si system of Au-contaminated and thermally oxidized n-type Si(001) have been investigated using XPS and alternating current surface photovoltage (AC SPV) techniques. On the basis of XPS analyses, in Au-contaminated (2 × 1015 atoms/cm 2) and thermally oxidized Si surfaces between 823 and 973 K, the Au existed both on the top of the SiO2 and the SiO2/Si interface as a cluster that did not make bonds with other elements such as O and H. The resulting Au/n-type Si Schottky barrier causes an occurrence of frequency-dependent AC SPV, demonstrating that the Si surface was depleted and/or weakly inverted. This result indicates that the Au/n-type Si Schottky barrier (calculated to be 0.70 eV) survived at the SiO2/Si interface even after the thermal oxidation. As the temperature increased higher than 1023 K, the Au at the SiO2/Si interface diffused into bulk Si, resulting in drastic reduction of AC SPV. On oxidation kinetics between 1023 and 1173 K, Au is thought to act as a catalyst and to promote the SiO2 growth at the Si surface, resulting in enhanced oxidation. Copyright © 2008 John Wiley & Sons, Ltd.