High-throughput screening of phase-engineered atomically thin transition-metal dichalcogenides for van der Waals contacts at the Schottky-Mott limit

A main challenge for the development of two-dimensional devices based on atomically thin transition-metal dichalcogenides (TMDs) is the realization of metal-semiconductor junctions (MSJs) with low contact resistance and high charge transport capability. However, traditional metal-TMD junctions usually suffer from strong Fermi-level pinning (FLP) and chemical disorder at the interfaces, resulting in weak device performance and high energy consumption. By means of high-throughput first-principles calculations, we report an attractive solution via the formation of van der Waals (vdW) contacts between metallic and semiconducting TMDs. We apply a phase-engineering strategy to create a monolayer TMD database for achieving a wide range of work functions and band gaps, hence offering a large degree of freedom to construct TMD vdW MSJs with desired contact types. The Schottky barrier heights and contact types of 728 MSJs have been identified and they exhibit weak FLP (-0.62 to -0.90) as compared with the traditional metal-TMD junctions. We find that the interfacial interactions of the MSJs bring a delicate competition between the FLP strength and carrier tunneling efficiency, which can be utilized to screen high-performance MSJs. Based on a set of screening criteria, four potential TMD vdW MSJs (e.g., NiTe2/ZrSe2, NiTe2/PdSe2, HfTe2/PdTe2, TaSe2/MoTe2) with Ohmic contact, weak FLP, and high carrier tunneling probability have been predicted. This work not only provides a fundamental understanding of contact properties of TMD vdW MSJs but also renders their huge potential for electronics and optoelectronics.