Ellipsometric study of thermally evaporated germanium thin film.

The optical properties of thermally evaporated germanium thin films in the spectral range 0.3-1.7 mum were studied with spectroscopic ellipsometry. The microstructure of these films, including their crystallinity, density, surface morphology, and surface oxidation, was analyzed with x-ray diffraction, Rutherford backscattering spectrometry, atomic force microscopy (AFM), and Auger electron spectrometry (AES). Parameters such as the surface roughness and surface-oxidation-layer thickness, derived from AFM and AES measurements, were incorporated into our optical model. The complex index of refraction (n and k) of the films was determined throughout the above spectral range and compared with that of single-crystal germanium.