Two-dimensional MoS2/Ti2CX2 (X = S, Se, Te) heterostructures with tunable electrical contact type

The tunable electrical contact type in van der Waals (vdW) heterostructures plays an important role in promoting the efficiency of ultrathin electronic devices. From the first-principles calculations, the electronic properties and electrical contact type of the MoS2/Ti2C heterostructure and its ramifications MoS2/Ti2CX2 (X = S, Se, Te) heterostructures are verified. The strong interfacial interaction is found in pristine MoS2/Ti2C heterostructure, resulting in the metallization of MoS2 layer. The functionalization of S, Se, and Te atoms can weaken the interfacial interaction, forming metal-semiconductor contact. The p-type Schottky contact is formed in MoS2/ Ti2CS2 and MoS2/Ti2CSe2 heterostructures, while Ohmic contact is formed in MoS2/Ti2CTe2 heterostructure. The application of external electric field can efficiently modulate the contact type of MoS2/Ti2CX2 (X = Se and Te) heterostructures. The discrepancy of electron affinity of S, Se, and Te atoms leads to the different interlayer charge transfer, and thus the different electrical contact type can be realized in MoS2/Ti2CX2 (X = S, Se, Te) heterostructures. The tunable contact type makes these heterostructures become potential candidate materials for enhancing the nanoelectronic devices' efficiency.