SAMPLE DEPOLARIZATION EFFECTS FROM THIN-FILMS OF ZNS ON GAAS AS MEASURED BY SPECTROSCOPIC ELLIPSOMETRY

Thin films of ZnS grown on GaAs by laser ablation are examined using spectroscopic two-channel polarization modulation ellipsometry (2-C PME). It is found that variations in the film thickness over the illumination spot result in the quasidepolarization of the incident light, which can be measured directly using 2-C PME. Quantitative fits of the ellipsometry data using a distribution-of-thicknesses model agree with independent reflectivity measurements of the thickness gradient, and allow for the accurate determination of the optical functions of the ZnS film.