Self‐Powered, Ultra‐Sensitive InGaAs/ITO Nanowire Radial Junction Infrared Photodiode for Low Flux Imaging at Room Temperature

ABSTRACT Shortwave infrared (SWIR) photodetection and imaging are of increasing importance for many emerging applications, such as optical and quantum communications, night vision, biomedical imaging and sensing. While planar InGaAs and Ge‐based SWIR photodetectors are the current state‐of‐the‐art, it is challenging to achieve single‐photon level sensitivity at non‐cryogenic temperatures due to their high dark current and thermal noise. Here, we demonstrate a highly sensitive self‐powered InGaAs nanowire photodetector with single‐photon‐level sensitivity at 1310 nm. The device utilizes a p+ InGaAs/Indium Tin Oxide (ITO) radial heterojunction nanowire structure, enabling strong optical confinement and efficient carrier extraction. It demonstrates a detection sensitivity down to 118.1 pW at room temperature and 6.5 pW at 223 K, corresponding to two photons per pulse of a 1310 nm laser excitation at 20 MHz with the noise equivalent powers of 1.59 × 10 −13 W Hz −1/2 and 2.18 × 10 −15 W Hz −1/2 respectively. The photodetector maintains a high signal‐to‐noise ratio of 58 dB at 1550 nm and cut‐off frequency of 15 MHz. Also, single‐pixel imaging under illumination down to ∼580 µW cm − 2 , showcasing the robust imaging capability under extremely low‐light conditions. Our results highlight the potential of nanowire‐based heterojunction photodetectors for the development of next‐generation, low‐cost, high‐performance SWIR photodetection and imaging technology.