Abstract: A back surface point contact silicon solar cell having improved characteristics is fabricated by hydrogenating a silicon-silicon oxide interface where hydrogen atoms are diffused through silicon nitride and silicon oxide passivating layers on the surface of a silicon substrate. In carrying out the hydrogenation, the substrate and passivation layers are placed in a hydrogen atomsphere at an elevated temperature of at least 900.degree. C. whereby hydrogen atoms diffuse through the two passivation layers. Self-alignment techniques are employed in forming small-geometry doped regions in the surface of the silicon substrate for the p-n junctions of the solar cell. Openings are formed through the passivation layers to expose first surface areas on the substrate, and a doped silicon oxide layer is then formed over the passivation layers and on the exposed surface areas.