Phase inversion in rotational anisotropy of second harmonic generation at Si(001) interfaces

Abstract

The phase of the azimuthal dependence of second-harmonic generation from Si(001) interfaces is observed to undergo an inversion for appropriate polarization configurations. The azimuthal dependence is due to interference between second-harmonic generation from bulk anisotropic tensor elements and isotropic elements, which include both bulk and surface terms. The inversion can be induced by either varying the photon energy or by surface modification. In the former case, the inversion is ascribed to the presence of a resonance in the surface contribution and it enhances the ability to identify resonance positions. The inversion due to surface modification is attributed to the corresponding change in the interfacial electronic state.