Ion-implanted laser-annealed p+ and n+ regions. A potential solution for industrially feasible high-efficiency n-type interdigitated back-contact solar cells

The main challenge for interdigitated back-contact (IBC) solar cells is to reduce the fabrication complexity, which consists of multiple high-temperature processing and patterning steps. Patterned ion implantation has been proposed to simplify the manufacture of IBC solar cells, and the annealing of boron and phosphorus implanted areas is still a problem for the application. In this study, a new method consisting of laser annealing and a subsequent low-temperature oxidation (LA&OX) has been developed to co-anneal boron implanted p+ and phosphorus implanted n+ regions by a single step. We found that an additional laser annealing before oxidation could improve the electrical properties of boron-implanted p+ regions effectively; however, it has almost no effect on the phosphorus-implanted n+ regions. An industrially feasible IBC solar cell fabrication technology has been proposed based on the patterned ion implantation and LA&OX processing. The main fabrication steps of the IBC solar cell could be reduced to ten steps, and only one high-temperature oxidation step is required. As-designed IBC cell shows a potential efficiency higher than 23% according to simulations with the experimental parameters.