A facile route to a high-quality graphene/MoS vertical field-effect transistor with gate-modulated photocurrent response

Two-dimensional layered materials, such as graphene (Gr) and molybdenum disulfide (MoS), have become fascinating and exciting candidates for next-generation electronic device materials. Their vertical combinations have led to novel electronic and photonic devices. We fabricated vertical field-effect transistors (FETs) with h-BN/Gr/MoS/Mo multi-heterostructures. A facile route was followed to design high-quality vertical FETs with improved performance. MoS was directly transferred to SiO/h-BN/Gr without using any polymer, which produced a clean interface between Gr and MoS. A high current ON-OFF ratio of ∼10 was demonstrated with a high current density of ∼10 A cm. Our results were attributed to the high-quality bottom Gr on h-BN, the top-most molybdenum metal contact, and the clean interface between Gr and MoS. The photoresponse of vertical FETs was also investigated under deep ultraviolet irradiation. The current density and photocurrent response of these vertical devices were strongly dependent on the back-gate voltage.