Deposition of barrier layers for thin film solar cells assisted by bipolar substrate biasing

For the development of diffusion and insulation barriers for thin film solar cells on unpolished steel with a rough surface as substrate, investigations of the shape of deposited SiO_x layers in dependence on an applied substrate biasing are carried out. Si-wafers with a well-defined surface structure in the range of micrometre are used as 'model' substrate. As a result, the deposition in the indentations of this surface is much higher in the case of a biased substrate. To determine the influence of the bias on the molecular structure, first investigations of the deposited layer without an applied bias are performed with in situ Fourier Transform InfraRed (FTIR) spectroscopy. Hence the molecular composition of the films is monitored during the deposition. In these spectra the Berreman effect occurs and is analysed.