Schottky Barrier Heights of Metallic-Semiconducting Transition-Metal Dichalcogenide Vertical and Lateral Heterostructures

Low resistance contacts to two-dimensional materials continue to be a limiting factor to obtaining the intrinsic performance limits of these materials. One approach to reduce the contact resistance to semiconducting transition metal dichalcogenides (TMDs) is to improve the interface between the metal and the TMD semiconductor. To address this, we investigate the use of 2D metallic TMDs (MX₂; M=Ta, Nb; X= S, Se, Te) as metal contacts to 2D semiconducting TMDs (MX₂; M=Mo, W; X= S, Se, Te). We determine the Schottky barrier heights of the monolayer semiconducting TMDs such as MoSe₂, WSe₂ and MoTe₂ with the monolayer metallic TMDs such as TaS₂, NbS₂, NbSe₂, TaSe₂ in both vertical and horizontal heterostructures using ab initio density-functional theory (DFT). For the horizontal heterostructures, two types of interface geometries are considered, armchair and zigzag. A vertical MoTe₂-NbSe₂ heterostructure gives a minimum p-type Schottky barrier of 0.11 eV. The horizontal armchair MoSe₂-TaS₂ heterostructure results in a negative Schottky barrier of 61 meV.