Enhanced current rectification and self-powered photoresponse in multilayer p-MoTe/n-MoS van der Waals heterojunctions.

Vertically stacked van der Waals (vdW) heterojunctions based on two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted a great deal of attention and have created a powerful new material platform for novel, high-performance electronic and optoelectronic devices. Here, we report the construction of multilayer p-MoTe/n-MoS vdW heterostructures with remarkable rectification behavior, self-powered photoresponse and distinct photosensitivity at different laser wavelengths and power densities. Field effect transistors (FETs) fabricated by MoTe/MoS heterojunctions exhibit excellent gate-tunable rectification behavior and p-n junction transport characteristics, with the n-type dominating. The MoTe/MoS heterojunction devices generate a self-powered photocurrent at zero bias voltage with a considerable on-off ratio reaching ∼780 and achieve a stable and fast photoresponse, due to the type-II band alignment facilitating efficient electron-hole separation. Utilizing the advantages of a p-n junction with type-II band alignment, this MoTe/MoS vdW heterostructure provides more opportunities for future electronic and optoelectronic applications.