Light modulation of negative differential resistance in MoS₂/h-BN/WS₂ unipolar barrier photodetector

Negative differential resistance (NDR) has enormous potentiality in various electronic devices such as oscillators, multipliers and multivalued logic. However, electrically controlled NDR behavior leads to complex hardware structures and an increase in power consumption, which hinders its practical integrated applications. This paper proposed a new NDR behavior excited and modulated by light in MoS₂/h-BN/WS₂ nBn unipolar barrier photodetector. This structure can effectively suppress the dark current and greatly reduce the power consumption. At 1 V bias under 488 nm laser irradiation, the device realizes dark current of 1.9 pA, on/off ratio of 3 × 10⁶, fast response time of 3 μs and visual imaging ability. The NDR behavior can be modulated by light effectively, and the ternary phase diagram of the NDR region and its mechanism have been illustrated. The device shows a peak-to-valley current ratio of 4.7 and a peak current density of 25.2 mA/cm², and has been successfully applied to oscillators, inverters, gate logic operations and image processing. The use of light as the control terminal of NDR behavior broadens the integration and application range of the NDR device, which provides a scientific basis for various circuit applications modulated by optical NDR behavior.