Charge-Induced Lattice Compression in Monolayer MoS2

Electron beam or photonic excitation of localized surface plasmon resonances (LSPRs) in gold nanoparticles and their subsequent nonradiative relaxation create a nonuniform charge distribution near the metal–semiconductor interface via hot-electron injection from gold nanoparticles to the monolayer MoS2 conduction band states. These charge domains induce lattice compression in the MoS2 lattice because of the inverse piezoelectric response arising due to the noncentrosymmetric nature of the crystal lattice. Our high-resolution transmission electron microscopy studies reveal that as much as 9–10% biaxial compressive strain is generated in free-standing monolayer MoS2 in the vicinity of gold nanoparticles, which relaxes rapidly within 50 nm from the edge of the gold nanoparticle. The metal interface-induced hot-electron injection via photonic excitation of LSPRs and the resultant lattice distortion also manifest in shifts as well as broadening of A1g(Γ) and E2g1(Γ) Raman modes of the monolayer MoS2 in presenc...