An ellipsometric analysis of CVD-diamond films at infrared wavelengths Original Research Article

The ellipsometric measurements of diamond films, which were deposited onto polished [100]-oriented silicon and rough alumina ceramic substrates by hot filament chemical vapor deposition (HFCVD) technique, have been performed over the spectral range from 3 to 12 μm. The parameters of the films, namely, film thickness and volume fraction for each constituent have been calculated from the ellipsometric data by the best fitting procedure using the optimized model. A two-layer stack with about 870-nm thick surface rough layer on top of diamond basis can be perfectly used to simulate the films on silicon substrates. However, the films on alumina substrates cannot be well described by the two-layer model. For the sake of good fit, a three-component interface layer, which consists of 64.13±4% alumina, 23.34±3% diamond and 12.53±1% void, must be appended to the model by Bruggeman effective medium approximation.