Simultaneous Imaging and Energy Harvesting in CMOS Image Sensor Pixels

We present a prototype CMOS active pixel that is capable of simultaneous imaging and energy harvesting without introducing additional in-plane p-n junctions. The prototype pixel uses a vertical ${p}^{+}/{n}_{\text {well}}/{p}_{\text {sub}}$ junction that is available in standard CMOS processes. Unlike the conventional CMOS electron-based imaging pixels, where the ${n}_{\text {well}}$ region is used as a sensing node for image capture, we adopted a hole-based imaging technique, while exploiting the ${n}_{\text {well}}$ region for energy harvesting at a high fill-factor of >94%. To verify the feasibility, CMOS image sensors are fabricated and characterized. We successfully demonstrated that the energy harvesting can be achieved with a power density of 998 pW/klux/mm2, while capturing images at 74.67 pJ/pixel. The fabricated prototype device has achieved the highest power density among the recent state-of-the-art works and can self-sustain its image capturing operation at 15 fps without external power sources above ~60 klux of illumination.