Manipulation of band alignment in InSe/GaTe and InSe/InS van der Waals heterostructures

The two-dimensional (2D) group III-VI chalcogenide family is gaining growing attention due to its potential applications in future optoelectronic devices. The van der Waals (vdW) heterostructure give novel properties that do not appear in their components. Herein, by using first-principles calculations, we study the 2D InSe/GaTe and InSe/InS vdW heterostructures, considering stacking patterns, electronic structures, band alignment, in-plane and out-of-plane strains effects. Both heterostructures are indirect band gap semiconductors with gap values of 0.84 and 1.07 eV for InSe/GaTe and InSe/InS, respectively. The InSe/GaTe heterostructure possesses a typical type-II band alignment, where the electrons and holes are localized in the InSe and GaTe layers, respectively. However, the band alignment type is ambiguous for InSe/InS heterostructure because valence band maximum simultaneously contains both InSe and InS components. The application of strains can change the band alignment type and induce a semiconductor-metal transition for both heterostructures. Besides, type-II or type-I band alignment in InSe/InS heterostructure can be realized by means of external electric field. Our results suggest that the vdW heterostructures based on 2D group III–VI chalcogenide family possess the tunable band alignment and band gap, which are very significant in the optoelectronic devices.