Tunable Schottky and ohmic contacts in the Ti₂NF₂/α-Te van der Waals heterostructure

Two dimensional α-Te holds great promise in optoelectronic devices because of its high mobility and excellent environmental stability. In this study, the electronic structures and interfacial contact characteristics of the Ti₂NF₂/α-Te van der Waals heterostructure are investigated by means of first-principles calculations. It is found that p-type Schottky contacts with a Schottky barrier (SB) of 0.21 eV are formed at the Ti₂NF₂/α-Te interface. By applying external electric fields or controlling the interlayer coupling between the Ti₂NF₂ and α-Te monolayers, the SB height can be effectively tuned, and all the n-type Schottky, p-type Schottky, n-type ohmic and p-type ohmic contacts can be achieved. Such an extremely high tunability is further found to be closely associated with the charge transfer at the interface, as well as the interface dipole and the potential step. Our results provide an avenue for the design of future α-Te-based electronic devices with high performance.