Theoretical approach to boosting NH3-sensing based on GeSe/SnS vdW heterostructure with strain modulation

Abstract

Stacking multiple two-dimensional materials to form a heterostructure is emerging as an effective way for tuning gas-sensitive properties. In this work, the GeSe/SnS van der Waals (vdW) heterostructure with Janus structure was constructed and investigated via first-principles calculations. The formation of the GeSe/SnS vdW heterostructure leads to spontaneous symmetry breaking and energy level splitting of the system, bring about new electronic properties. The GeSe/SnS heterostructure shows a smaller band gap of 1.272 eV, with an electron-rich layer formed by interlayer charge transfer (0.171 e) due to the built-in electric field, which promotes the NH3 adsorption energy and charge transfer ability. Further investigate was performed for the effect of compressive strain on the band gap and interface structure of GeSe/SnS heterostructure. The application of −6% compressive strain causes the largest work function change (0.423 eV) of the GeSe/SnS heterostructure before and after NH3 adsorption on the GeSe layer, with maximum adsorption energy (0.805 eV) and charge transfer (0.089 e), which implies the enhanced interaction between NH3 and heterostructure. Our work theoretically predicts that constructing a heterostructure and applying strain can synergistically enhance the NH3 response of SnS and GeSe, which paves the way for gas-sensing enhancement studies of black phosphorus-like materials.