Spectroscopic ellipsometry and atomic force microscopy studies of RF sputtered Cd1-xMnxTe films

Automatic spectroscopic ellipsometry (SE) with a 0.75 - 6.5 eV photon energy range was used together with atomic force microscopy to investigate surface optical and structural characteristics of as-deposited, annealed, and chloride treated Cd_1-xMn_xTe thin films. The E₁, E₁ + Δ₁, and E₂ critical-point structures were clearly observed in the SE data for as-deposited samples. The variation of the pseudodielectric function for as-deposited samples was observed under different surface preparation and measurement conditions by in situ SE. The AFM images of the corresponding as-deposited samples revealed variations in surface morphology that were consistent with the SE results. For chloride treated samples, the pseudodielectric function was much different from that of as-deposited samples. This difference was due not only to oxidation of the surface, but also to a disruptive change of the bulk film under such annealing conditions.