Time-Integrated Phototransistor Based on Photoactive Gate Engineering for Ultra-Weak Light Detection.

Miniaturized weak-light detection is constrained by the reliance on external amplification and signal-accumulation circuitry. Here, we report a time-integrated phototransistor (TIPT) based on γ-InSe photoactive gate architecture that enables intrinsic signal amplification and temporal accumulation within a single device. This architecture enables continuous integration and amplification of weak optical signals, achieving ultra-low-power detection with high photosensitivity, with detection limits down to 29 fW at 520 nm and 4.2 pW at 980 nm. The accumulation process is dynamically tunable and resettable via gate control. A single-device sequential scanning reconstruction further validates improved image contrast through temporal integration due to the robustness and repeatability of TIPT. These results establish time-integrated photogating as a strategy for ultra-low-power photodetection, offering a compact and energy-efficient platform for miniaturized weak-light imaging.