Heterojunction Floating-gate Phototransistors for Ultraweak Short-Wavelength Infrared Photodetection

Abstract

Short-wavelength infrared (SWIR) photodetectors with high sensitivity are indispensable for detecting subtle object variations under low-light conditions, a capability that supports advancements in artificial intelligence. However, commercial approaches for low-light photodetection, such as photomultiplier tubes and avalanche photodiodes, often require high operating voltages, lack compatibility with modern microelectronic technologies critical forintegrated optoelectronic systems. Herein, we present a hybrid phototransistor integratingcarbon nanotube thin film field-effect transistors (CNT-FETs) with lead sulfide colloidalquantum dot (PbS CQD) heterojunction photodiodes, where the PbS CQD photodiode functionsas a floating-gate modulating the CNT-FET channel current. Under 1350 nm illumination, thephototransistor demonstrates a minimum detection light power density of 0.39 nW cm-2, withresponsivity and D* of 1.02 E5A W-1 and 8.1 E13 Jones, respectively, while the external quantum efficiency (EQE) reaches an impressive 9.4 E6 %. This innovative phototransistor showcases significant potential for both photodetection and imaging applications within the weak SWIR environment.