First-principles study on electronic states of InSe/Au heterostructure controlled by strain engineering.

The development of low-dimensional multifunctional devices has become increasingly important as the size of field-effect transistors decreases. In recent years, the two-dimensional (2D) semiconductor InSe has emerged as a promising candidate for applications in the fields of electronics and optoelectronics owing to its remarkable spontaneous polarization properties. Through first-principles calculations, the effects of the polarization direction and biaxial tensile strain on the electronic and contact properties of InSe/Au heterostructures are investigated. The contact type of InSe/Au heterostructures depends on the polarization direction of InSe. The more charge transfers from the metal to the space charge region, the biaxial tensile strain increases. Moreover, the upward polarized InSe in contact with Au maintains a constant n-type Schottky contact as the biaxial tensile strain increases, with a barrier height of only 0.086 eV at 6% strain, which is close to ohmic contact. On the other hand, the downward polarized InSe in contact with Au can be transformed from p-type to n-type by applying a biaxial tensile strain. Our calculation results can provide a reference for the design and fabrication of InSe-based field effect transistors.