Electronic and optical properties of monochalcogenides van der Waals heterostructure from atomistic simulations

Layering two-dimensional (2D) ferroelectric monochalcogenides in heterostructures offers a powerful approach to tailor the properties of materials and devices for a wide range of applications, including field-effect transistors, nanoelectronics, and sensors. Here, density functional theory (DFT) is used to investigate the electronic and optical properties of monochalcogenides van der Waals heterostructure GeS/SnS. Formation energy and dynamical dispersions confirm the chemical and dynamical stability of the heterostructure. The heterostructure shows the indirect band gap of 1.14 eV by using PBE, and a band gap of 2.54 eV by using HSE06 hybrid functional. Exotic properties can be achieved by computationally engineering 2D van der Waals (vdW) materials and their heterostructures with a suitable choice of stacking order, thickness, and interlayer interactions. Biaxial strain tunes the electronic properties, and indirect to direct band gap conversion of heterostructure is found under biaxial strain. We further investigate the optical properties of heterostructure and show their potential use in ferroelectric memory devices.