Enhanced-performance self-powered photodetector based on multi-layer MoS_(2) sandwiched between two asymmetric graphene contacts

Self-powered photodetectors can convert light into electrical signals without external power input and are widely used in applications such as imaging,sensing,communication,and security.The most popular approach for constructing a self-powered photodetector is typically based on the fabrication of an asymmetric metal-semiconductor(MS)contact;however,this technique is seriously limited by the Fermi-level pinning effect.Here,we report a room-temperature photodetector based on multi-layer MoS_(2) sandwiched between two separated asymmetric graphene contacts.Our photodetector was driven by the built-in electric field generated by a van der Waals(vd W)contact instead of the traditional MS contact.Operating under zero-bias voltage,the highest photoresponsivity of 0.63 AW^(-1) and a specific detectivity of 7.71×10^(12) Jones were achieved at a wavelength of 450 nm with 0.08μW cm^(-2) incident power intensity.Compared with devices using symmetric contacts,a high ON/OFF current ratio of approximately 1520 and a fast response time on the order of microseconds were also observed in our asymmetric graphene contact device.Our experimental results may open a novel way toward the realization of vd W contacts for the fabrication of selfpowered photodetectors.