Computational study of phase engineered transition metal dichalcogenides heterostructures

Abstract

Van der Waals heterostructures composed of the same transition metal dichalcogenide with different structural phases are promising for optimizing the electrical contacts in two-dimensional transistors. While most theoretical studies are focused on the “more stable” 1T′ or Td phase, experiments show that the metastable 1T phase can also form heterostructure with the 2H phase. However, the intrinsic properties of these phase engineered van der Waals heterostructures are not clear. By first–principles calculations, we investigate the structural and electronic properties of the MX2 (M=Mo, W; X=S, Se, Te) heterostructures composed by the semiconducting 2H and metallic 1T phases. A very small amount of electron transfers from 1T to 2H phases in the checked heterostructures, rendering the 2H phase undoped or only slightly N–doped. The existence of the Schottky barriers (0.39–0.94 eV) is found common in the free-standing 2H/1T MX2 heterostructures. In addition, the zero tunnel barrier heights in the checked heterostructures are advantageous for achieving high charge injection rate.