Gate dielectric-induced lattice strain and band gap tuning in van der Waals 2D semiconducting channels

Gate dielectric materials are paramount in field-effect transistors (FETs), as they not only modulate carrier concentration but also induce local perturbations in the lattice structure within the semiconductor channel, thus influencing device performance. While electrical measurements directly assess mobility and concentration under the influence of a gate electric field, they often fail to probe locally induced strain in the crystal structure of the channel around the junction. In this study, we utilized Raman spectroscopy to investigate electric field-induced lattice strain in van der Waals two-dimensional (2D) semiconducting channels through different gate dielectrics (hBN and air) at the junction. The experimental findings demonstrate that at the junction, the van der Waals heterostructure channel exhibits high electric field-induced local strain with the hBN gate dielectric, exhibiting an ∼1.6-fold enhancement for A_g¹, B_2g, A_g² E_2g¹, and A_1g as compared to the air dielectric, and further facilitates the tailoring of the gate-channel interfaces to optimize transistor performance through gating effects.