VICINAL SI(111) SURFACES STUDIED BY OPTICAL 2ND-HARMONIC GENERATION - STEP-INDUCED ANISOTROPY AND SURFACE-BULK DISCRIMINATION

By modifying a Si(111) surface through the introduction of a variable number of steps, the anisotropic surface and bulk contributions to the optical second-harmonic generation could be determined separately and were found to be of the same order of magnitude for a Si-SiO2 interface. This approach is based on the lowering of the surface symmetry by the steps and by the apparent enhancement of the nonlinear susceptibility at the step edges. © 1990 The American Physical Society.