Two-dimensional SnSe/GeSe van der Waals heterostructure with strain-tunable electronic and optical properties

Abstract Two dimensional materials have a bright prospect for some strain-tunable applications due to their ultrathin and flexible characteristics. In this work, SnSe/GeSe van der Waals heterostructure is first constructed based on the GeSe and SnSe monolayers, and then their electrical and optical properties are investigated by first-principles calculations. Furthermore, the effects of strain on the electrical and optical properties of SnSe/GeSe are also studied. SnSe/GeSe is found to be a direct semiconductor with a band gap range from 0.19 eV to 0.83 eV, which can be flexiblely tuned by the in-plane strain. Under the uniaxial strains e a and e b , the tunable ranges of strain and direct bandgap are much smaller than those under the biaxial strain e u . Transformation between direct and indirect bandgap in SnSe/GeSe occurs under some applied strains. Being capable to absorb ultraviolet and far-ultraviolet light, SnSe/GeSe exhibits higher peak of absorption coefficient and the imagery part of dielectric function than those of GeSe and SnSe. Under small in-plane strains range from −0.06 to 0.06, anisotropy of SnSe/GeSe can be found in the optical parameters. The peaks of the absorption coefficient and dielectric function both increase with the decrease of strain. The light absorption capability of SnSe/GeSe becomes stronger with smaller in-plane strains, in which the biaxial strain is the most effective way to tune the optical properties. With these intriguing properties, SnSe/GeSe will be a promising two-dimensional material for applications in nanomechanics and optoelectronics.