Fig. 3

Electrical characterization of heterojunction FET devices. a Schematic diagram of the four-electrode Ta₂NiSe₅-WS₂ vdW heterojunction FET device. Inset: SEM image of the device channel (left). AFM profile and AFM thickness curve of the device (right). b Schematic diagram of the band structure of Ta₂NiSe₅ and WS₂ after contact. c IV curve of the source-drain electrode of each device in the four-electrode device. d On-off ratio curve and rectification ratio curve of the heterojunction device. e Experimental measured noise current of the devices at different gate voltages. f IV curves of the source-drain electrode of the heterojunction device under no light exposure and illumination with lasers at 635, 808, and 1550 nm. g IV curves of the source-drain electrode of the heterojunction device under no light exposure and with radiation at 0.024 THz and 0.171 THz