Patent ID: 8889462

Claim:
A method of forming photovoltaic concentrator solar cells from a semiconductor wafer having a front surface and a rear surface comprising the following steps: (a) doping the rear surface of said wafer so as to provide a first doped region at the rear of said wafer; (b) depositing passivation layers on the front and rear surface to provide a dopant mask; (c) forming a deep groove in the rear surface through the passivation layer, to within one diffusion length of the front surface of the wafer; (d) doping said rear surface so as to provide a second doped region solely in the deep groove, said second doped region being oppositely doped to said first doped region, the passivation layers acting as a mask to confine diffusion into the wafer to the deep groove only; (e) forming an opening, through the rear passivation layer to the first doped region; and (f) forming electrical contacts on said rear surface to electrically connect to the first and second doped regions.