Tunable electronic and optical properties of MoTe2/InSe heterostructure via external electric field and strain engineering.

ABSTRACT

Based on first-principles calculation under density functional theory, the geometry, electronic and optical properties of the MoTe2/InSe heterojunction have been investigated. The results reveal that the MoTe2/InSe heterojunction has a typical type-Ⅱ band alignment and exhibits an indirect bandgap of 0.99 eV. In addition, the Z-scheme electron transport mechanism is capable of efficiently separating photogenerated carriers. The bandgap of the heterostructure changes regularly under applied electric field and exhibits a significant Giant Stark effect. Under an applied electric field of 0.5 V Å-1, the band alignment of the heterojunction shifts from type-Ⅱ to type-I. The application of strain produced comparable changes in the heterojunction. More importantly, the transition from semiconductor to metal is completed in the heterostructure under the applied electric field and strain. Furthermore, the MoTe2/InSe heterojunction retains the optical properties of two monolayers and produces greater light absorption on this basis, especially for UV light. The above results offer a theoretical basis for the application of MoTe2/InSe heterostructure in the next generation of photodetectors.