An improved solar cell is disclosed. To create the internal p-n junction, one surface of the substrate is implanted with ions. After the implantation, the substrate is thermally treated. The thermal process distributes the dopant throughout the substrate, while repairing crystal damage caused by implantation. After the thermal process, residual crystal damage may remain, which adversely impacts solar cell efficiency. In order to further reduce the residual damage, the uppermost portion of the surface is then removed, thereby eliminating that portion of the substrate where most of the defects reside. The lower defect concentration reduces recombination and improves efficiency of the solar cell.