Fabrication of silicon heterojunction solar cells with a boron-doped a-Si:H layer formed by catalytic impurity doping

Abstract

We investigate the effect of boron (B) catalytic impurity doping (Cat-doping), a low-temperature doping method by exposing to catalytically generated dopant radicals, on hydrogenated amorphous silicon (a-Si:H) films and the influence of the electrical properties of indium tin oxide (ITO) films on the tunneling conduction of carriers through the ITO/a-Si:H interfaces. The usage of ITO films with higher carrier density and B Cat-doped a-Si:H films formed with the addition of H2 enhances carrier tunneling through the a-Si:H/ITO interfaces. We also evaluate the current density–voltage (J–V) characteristics of Si heterojunction (SHJ) solar cells with a B Cat-doped a-Si:H layer as an emitter layer. In the case of B Cat-doping with the addition of H2, we obtain a SHJ solar cell which shows a conversion efficiency (η) of 12.6% and an open-circuit voltage (Voc) of 617 mV. The postannealing of the SHJ cells is effective to improve their Voc and η. These results will lead to the application of B Cat-doping on heterojunction back-contact solar cells in the future.