Drawing the Most Power From Low-Cost Single-Well 1-mm2 CMOS Photovoltaic Cells

Photovoltaic (PV) cells can generate 100× more power from light than other transducers can from motion, radiation, and heat. Although custom multijunction nonsilicon and multiwell complementary metal-oxide-semiconductor (CMOS) cells output more power, single-well process technologies cost less. Amorphous cells cost even less but output less power. However, with only a small window of light available, tiny CMOS cells output little. This brief explores and proposes open-terminal single-well CMOS PV cell configurations that output more power than competing low-cost CMOS cells in literature. Measurements with 0.35-μm 1 × 1-mm
²
single-well CMOS cells show that deeper and lighter doped junctions generate higher power than shallower junctions, and double-junction configurations output even higher power. This is why sunlight on N
⁺
in P substrate and N well in P substrate cells outputs 6 and 98 μW and on shorted and open-terminal P
⁺
in N well in P substrate structures outputs 132 μW. Opening the P
⁺
terminal outputs even more power because P
⁺
metal, which blocks light, is no longer necessary.