CHARACTERIZATION OF SURFACE-POTENTIAL AND STRAIN AT ULTRATHIN OXIDE SILICON INTERFACE BY PHOTOREFLECTANCE SPECTROSCOPY

Si surface potential and strain at the Si-SiO2 structure with a therma lly grown or a native SiO2 ultrathin film have been characterized by p hotoreflectance (PR) spectroscopy. The surface potentials of Si-SiO2 s tructures are determined from the modulation light intensity dependenc e of the PR signal intensity. Although the signal intensity decreases drastically with increasing SiO2 film thickness, it can be increased b y applying dc bias voltage and increasing the surface potential of Si. The strains at the Si surface have been obtained by an analysis of th e transition energy shift in the SiO2/Si structure with a thermally ox idized ultrathin film.