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In order to increase the conversion efficiencies of silicon solar cells, advanced cell structures with selectively doped areas receive an increasing interest. There is a strong need to separate the contacted diffusion profiles from the non-contacted. On the one hand, a high dopant concentration in the contact regime reduces the series resistance losses mainly due to lowered contact resistance. Additionally recombination is reduced by shielding the minority charge carriers from surface at the contact. On the other hand a low dopant concentration in the non-contact regime reduces the recombination losses and optimizes the spectral response of the cell.In this work phosphorus doped silicon oxide layers are used as a diffusion source for tube furnace diffusion processes. It is shown that the sheet resistance of the diffused area is controlled by the silane gas flow during the deposition of phosphorus doped silicon oxide. In order to analyze the influence of the diffused areas on the saturation current densities, symmetrical carrier lifetime samples are prepared. Therefore a stack system consisting of a thermally grown silicon dioxide and silicon nitride is used for passivation purposes on textured samples.

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In this study, the feasibility of creating one dielectric layer system acting simultaneously as antireflection coating, phosphorous doping source, masking against metal plating, and surface passivation is presented. Moreover, a similar layer stack is described, which behaves as rear-side surface passivation, boron dopant source, and internal reflection mirror. The optical characteristics of these layers are especially investigated and optimized for a solar cell's front-and rear-side coating. By consequent use of the multifunctional layers, a totally diffused solar cell with rearside passivation and local rear contacts can be produced using only one wet chemical bath sequence, one multilayer vacuum step, and one high-temperature process. We present the first proof of concept for such a solar cell production using multifunctional plasmaenhanced chemical vapor deposition layers resulting already in a conversion efficiency of 18.3%.