Performance of n(+)-p-p(+) silicon solar cells fabricated through masked ion implantation

Attention is given to the dependence of such electrooptical characteristics as peak responsivity wavelength, spectral bandwidth, short-circuit current density, open circuit voltage, and conversion efficiency, on the implant parameters of energy, dose, and oxide thickness, for the case of n(+)-p-p(+) single crystal solar cells whose front junctions are formed by ion implantation of P-31(+) into p-wafers through a thermally grown SiO2 mask of variable thickness. An increase in short-circuit current density is noted for cells of up to 35 mA/sq cm under AM 1 conditions; the best industrially fabricated cells had conversion efficiencies of 14.3 percent and fill factors as high as 76.8 percent. Detailed explanations are furnished for anomalous experimental results and design guidelines.