AU STRUCTURES ON SI(111) STUDIED BY SPECTROSCOPIC ELLIPSOMETRY AND OPTICAL 2ND-HARMONIC GENERATION

Two optical techniques, spectroscopic ellipsometry (SE) and second har monic generation (SHG), have been used to follow the initial stages of ordered growth of Au on the Si(111) surface under ultra-high vacuum c onditions. Comparison of the linear and nonlinear optical response, as a function of coverage, shows that the nonlinear response is more sen sitive to submonolayer structural changes, for this system. Difference s in the linear optical response of amorphous and ordered interfaces i ndicate the necessity for more sophisticated approaches to microscopic modelling of ultra-thin film growth.