Ion implantation technique has been demonstrated to improve solar cell efficiency. In this study, we etched an as-implanted p-type wafer and then used an appropriate annealing condition to obtain an optimum surface doping profile for the emitter of a crystalline silicon solar cell. A SiO2 layer was used both as a barrier layer for anti-outdiffusion and a surface passivation layer, which was deposited before the annealing process. An improvement in solar cell efficiency was demonstrated by low-energy phosphorus ion implantation at a proper dose. (C) 2016 Elsevier Ltd. All rights reserved.