High-Performance Two-Dimensional Schottky Diodes Utilizing Chemical Vapour Deposition-Grown Graphene-MoS2 Heterojunctions.

Heterostructures based on two-dimensional (2D) materials have attracted enormous interest as they display unique functionalities and have potential to be applied in next-generation electronics. In this report, we fabricated three types of heterostructures based on chemical vapor deposition-grown graphene and MoS2. A significant rectification was observed in the Au-MoS2-Gr heterojunction, with a rectification ratio over 2 × 104. The rectifying behavior is reproducible among nearly all 44 devices and is attributed to an asymmetrical Schottky barrier at Au-MoS2 and MoS2-graphene contacts. This rectification can be tuned by external gating and laser illumination, which have different impact on the rectifying ratio. This modulation of the Schottky barrier is evidenced by output characteristics of two symmetrical heterostructures: Au-MoS2-Au and Gr-MoS2-Gr field-effect transistors. The effective heights of MoS2-graphene and MoS2-Au Schottky barriers and their response to back-gate voltage and laser irradiation were extracted from output characteristics of Au-MoS2-Au and Gr-MoS2-Gr field-effect transistors. The tuned Schottky barriers could be explained by the Fermi level change of graphene and MoS2. These results contributed to our understanding of 2D heterostructures and have potential applications in novel electronics and optoelectronics.