Ultraviolet-light-driven enhanced photoresponse of chemical-vapor-deposition grown graphene-WS2 heterojunction based FETs

Graphene and transition metal dichalcogenides (TMDCs), an emerging class of two-dimensional (2D) materials exhibiting excellent electrical and optical properties have shown a phenomenal advancement in optoelectronics and electronic technology. However, two-dimensional van der Waals heterostructures have gained profound interest due to additional functionalities over usual 2D devices. Here we demonstrated the photoconductive response of graphene-WS2 heterostructure at different backgate (Vg) and drain-source voltages (Vds) as a function of time, under UV illumination. An increase in photocurrent characteristics is observed as Vds varies from 0.3 V to 1 V. The response of photosensivity is tuned by varying the backgate voltage. The optical performance of graphene-WS2 phototransistor is evaluated by investigating the photoresponsivity (Rλ), detectivity (D*), external quantum efficiency (EQE) and linear dynamic range (LDR). These results suggest the TMDC-graphene heterostructure, as a good contender to be used in photosensing and optoelectronic applications.