Self-powered programmable van der Waals photodetectors with nonvolatile semi-floating gate

Tunable photovoltaic photodetectors are of significant relevance in the fields of programmable and neuromorphic optoelectronics. However, their widespread adoption is hindered by intricate architectural design and energy consumption challenges. This study employs a nonvolatile MoTe2/hBN/graphene semi-floating photodetector to address these issues. Programed with pulsed gate voltage, the MoTe2 channel can be reconfigured from an n±n to a p-n homojunction, and the photocurrent transition changes from negative to positive values. Scanning photocurrent mapping reveals that the negative and positive photocurrents are attributed to Schottky junction and p-n homojunction, respectively. In the p-n configuration, the device demonstrates self-driven, linear, rapid response (~3 ms), and broadband sensitivity (from 405 to 1500 nm) for photodetection, with typical performances of responsivity at ~0.5 A/W and detectivity ~1.6*10^12 Jones under 635 nm illumination. These outstanding photodetection capabilities emphasize the potential of the semi-floating photodetector as a pioneering approach for advancing logical and nonvolatile optoelectronics.