MoTe2/InN van der Waals heterostructures for gas sensors: a DFT study†

Abstract

Vertical van der Waals (vdW) heterostructures have shown potential for gas sensing owing to their remarkable sensitivity. However, the optimization process for achieving the best gas sensing performance is complicated by the heterostructure's reliance on both physical and electrical characteristics. This study employs density functional theory (DFT) to analyse the structural and electronic parameters of a MoTe₂/InN vdW heterostructure. The findings of this study indicate that the vdW heterostructure has a type-II band alignment with higher adsorption energy towards NH₃, NO₂, and SO₂ than the individual monolayers. In specific, the heterostructure is well suited for NO₂ detection but has limitations in reliably detecting NH₃ and SO₂ due to longer recovery times. We find significant hybridization between the adsorbate and interacting surfaces’ orbitals and a notable presence of NO₂ molecular orbitals in proximity to the Fermi level. Additionally, dielectric and work function modulations offer a viable means to develop optical-based gas sensors that can selectively detect NO₂. Our research provides valuable insights into vdW heterostructure design for high-performance gas sensors.