PROBING THE SILICON-SILICON OXIDE INTERFACE OF SI(111)-SIO2-CR MOS STRUCTURES BY DC-ELECTRIC-FIELD-INDUCED 2ND-HARMONIC GENERATION

The buried Si(111)-SiO2 interface has been studied in transmission thr ough planar Si-SiO2-Cr MOS structures using DC-electric-field-induced second-harmonic generation (EISHG). The rotational anisotropy and oxid e thickness dependence of EISHG have been measured. Multiple reflectio ns in the oxide layer and interference effects between field-dependent and field-independent contributions to the nonlinear polarization are shown to affect the shape of the EISHG bias dependence. From a simple model the relative size of field-dependent and field-independent cont ributions can be estimated. In this way, information about the interfa ce charge distribution can be obtained.