Characterization of single-photon sensing and photon-number resolving CMOS image sensors

Single-photon sensing and photon-number resolving image sensors are key to enabling projects that are not possible today. We present detector characterization results for four single-photon sensing and photon-number resolving backside illuminated complementary metal-oxide semiconductor (CMOS) image sensors. Eric R. Fossum and his team at Dartmouth College led early detector development and continues through Gigajot Technology Inc. The CMOS image sensors have pixels (1.1 μm pitch) that use small-capacitance floating diffusions to achieve deep sub-electron read noise (<0.5 e⁻ RMS). Characterization results include dark current, read noise, quantum efficiency, persistence, linearity, well depth. We also report on our ongoing work to use the image sensors for astronomical observations. We compare the performance of the four CMOS image sensors to that of state-of-the-art detectors, particularly with respect to the large UV/O/IR space telescope recommended by the 2020 Decadal Survey on Astronomy and Astrophysics.