A method that uses second-harmonic generation is applied to the study of the oxidized Si(111) surface by <i>in situ</i> control of thermal and synthetic oxide etching with monolayer atomic resolution. It is shown that the thin oxide layer that is adjacent to the Si surface (with a 5–10-Å thickness) exerts a strong influence on the reflected second-harmonic intensity. The contribution of the remaining bulk oxide is insignificant. Various contributions to the nonlinear polarization in the SiO<sub>2</sub>–Si interface, such as the static electric field, the inhomogeneous deformation, and the effect of a crystalline oxide layer, are considered.
© 1991 Optical Society of America
L. L. Kulyuk, D. A. Shutov, E. E. Strumban, and O. A. Aktsipetrov, "Second-harmonic generation by an SiO2–Si interface: influence of the oxide layer," J. Opt. Soc. Am. B 8, 1766-1769 (1991)