A method for the fabrication of a light-sensing diode in a high-resistivity semiconductor substrate. A high-energy implant of ions into the substrate is patterned to form an annular well of the same conductivity type as the substrate; followed by a second high-energy implant of the opposite conductivity type, within the center of the annulus; followed by a third implant, of lower energy and high dosage, to form a region of the first conductivity type extending laterally near the substrate surface. The resulting diode junction is thereby patterned to include two planes near the substrate surface, allowing incident light to traverse the junction twice.