High efficiency Si quantum dot heterojunction solar cells using a single SiO_X:B layer

Si quantum dots (QDs) have been fabricated from SiO₂/SiO_x multilayer structures to create a homogeneous size. However, this structure achieved much lower efficiencies than would be expected in the Si QD photovoltaic field. This is because Si QD generation and photoexcited carrier transport is restricted by the adjacent SiO₂ layer. In this study, we applied a single SiO_x:B layer fabrication method to the Si QD heterojunction solar cells. The number of generated Si QDs and the photo-excited carrier lifetime was maximized when the oxygen partial pressure and boron doping concentration parameters were 2.7 × 10^-5 Torr and 2.27 × 10²¹ atoms cm^-3, respectively. As a result, in excess of 17% power conversion efficiency for the Si QD heterojunction solar cell was achieved using the single layer method.