Within the photovoltaic industry, a lot of research is done in order to minimize losses which are created during the conversion of solar light to electrical energy. In a crystalline silicon solar cell light has to pass through several layers before it enters the silicon wafer where the electron-hole pairs are generated. As one can imagine, if more light reaches the active layer, more electron-hole pairs can be generated. It is highly desired that only one layer, the active layer, is absorbing photons of the solar spectrum. The active layers at the sunny side of the silicon wafer should be highly transparent for solar light. In addition to being transparent, these layers should be conductive to extract the generated charge carriers to the metal contacts. Current layers applied at the sunny side are not optimally transparent, so it is still possible to increase the efficiencies in the crystalline silicon solar cells. In this study, doped silicon oxide layers have been explored as a potential more transparent layer for passivation of both the silicon surface and the metal contacts. Two routes for the fabrication of doped silicon oxide layers were investigated: post-oxidation of doped polycrystalline silicon layers and post-doping of in-situ grown silicon oxide layers. To characterize this new type of material, several different measurement techniques have been applied to improve our understanding of Low-Pressure Chemical Vapor Deposition deposited silicon oxide passivating contact layers. It was found that the structure and composition of the layers is very different for these different routes. However, very good and stable surface passivation (minority carrier lifetime of >3ms) can be achieved with both types of silicon oxide layers. Also, sheet resistance measurements have indicated that phosphorus doping in silicon oxides is possible. For better insight into the electrical properties of these layers, further testing in electronic test structures is advised.