A surface region about 0.22 &mgr;m thick of cadmium‐annealed undopedn‐type CdTe single crystal was converted toptype by implantation of 60‐keV As+ions followed by a cadmium annealing. The electrical properties of thep‐type layer were measured as well as the photovoltaic properties of thep‐njunction formed in this way. For illumination by sunlight an open‐circuit voltage of 0.84 V was found in a cell with a solar efficiency of 3.0&percent;. The parameters of the junction were determined using a model designed to describe the spectral response of the cell.