The reflected optical second harmonic intensity from the Ge(111)/GeO2 inter
face has been measured in a dry nitrogen atmosphere as a function of the in
cident photon energy. The oxide layer was produced by thermally oxidizing a
Ge(111) substrate in pule oxygen gas at 823 K. We have found that the SH i
ntensity pattern as a function of the sample rotation angle around the surf
ace normal changes drastically in the photon energy range near h omega =1.1
7 eV in the p-polarized input and p-polarized output configuration. At this
resonance, the anisotropic SH response from the interface has a dominant c
ontribution to the SH intensity. (C) 2000 Elsevier Science B.V. All rights
reserved.