Boron doped SiOx dielectrics for bifacial n-type and p-type silicon solar cells

Bifaciality offers a high potential to increase the efficiency of industrial silicon solar cells and their integration to sustainable building design. However, not enough work has been presented on doped dielectrics for bifacial solar cells. In this work we show a study on p-doped SiOx layers for bifacial solar cells. We use a non-conventional gas precursor, hexamethyldisiloxane (HMDSO) for the silicon-oxygen source, mixed with diborane as the p-type dopant and carbon-dioxide as the additional oxygen source. Our analysis reveals that layers deposited with HMDSO are thermally stable compared to the case when silane is used. Electrochemical capacitance voltage and secondary ion mass spectrometry measurements confirm the formation of a uniform boron doped layer inside the silicon bulk. Furthermore, we found that the depth of p(+)-n and p(+)-p junction can be controlled by the deposition parameters and the time of thermal diffusion. Chemical analysis shows that carbon is accumulated at the dielectric/wafer interface due to a barrier formation inside the carbon rich silicon. The p-SiOx layers can be applied on n-c-Si and p-c-Si base material as an emitter and back surface field respectively, demonstrating a feasible bifacial solar cell device. (C) 2015 The Authors. Published by Elsevier Ltd.