Tunable Contact Types and Interfacial Electronic Properties in TaS/MoS and TaS/WSe Heterostructures.

Following the successful experimental synthesis of single-layer metallic 1T-TaS and semiconducting 2H-MoS, 2H-WSe, we perform a first-principles study to investigate the electronic and interfacial features of metal/semiconductor 1T-TaS/2H-MoS and 1T-TaS/2H-WSe van der Waals heterostructures (vdWHs) contact. We show that 1T-TaS/2H-MoS and 1T-TaS/2H-WSe form n-type Schottky contact (n-ShC type) and p-type Schottky contact (p-ShC type) with ultralow Schottky barrier height (SBH), respectively. This indicates that 1T-TaS can be considered as an effective metal contact with high charge injection efficiency for 2H-MoS, 2H-WSe semiconductors. In addition, the electronic structure and interfacial properties of 1T-TaS/2H-MoS and 1T-TaS/2H-WSe van der Waals heterostructures can be transformed from n-type to p-type Schottky contact through the effect of layer spacing and the electric field. At the same time, the transition from Schottky contact to Ohmic contact can also occur by relying on the electric field and different interlayer spacing. Our results may provide a new approach for photoelectric application design based on metal/semiconductor 1T-TaS/2H-MoS and 1T-TaS/2H-WSe van der Waals heterostructures.