Energy and charge transfer effects in two-dimensional van der Waals hybrid nanostructures on periodic gold nanopost array

Two-dimensional (2D) semiconducting MoS₂ and WSe₂ flakes grown by chemical vapor deposition were mechanically hybridized. A hexagonal boron nitride (h-BN) dielectric flake was inserted between MoS₂ and WSe₂ flakes to investigate the nanoscale optical properties of 2D van der Waals hybrid nanostructures. The fabricated MoS₂/WSe₂ and MoS₂/h-BN/WSe₂ van der Waals hybrid nanostructures were loaded on a periodic gold nanopost (Au-NPo) array to study energy and charge transfer effects at the surface plasmon resonance (SPR) condition. Nanoscale photoluminescence (PL) spectra of the 2D hybrid nanostructures were measured using a high-resolution laser confocal microscope (LCM). A shift of the LCM PL peak of the MoS₂/WSe₂ n-p hybrid nanostructures was observed owing to the charge transfer. In contrast, the shift of the LCM PL peak of the MoS₂/h-BN/WSe₂ n-insulator-p hybrid nanostructure was not considerable, as the inserted h-BN dielectric layer prevented the charge transfer. The intensity of the LCM PL peak of the MoS₂/h-BN/WSe₂ hybrid nanostructure considerably increased once the nanostructure was loaded on the Au-NPo array, owing to the energy transfer between the 2D materials and the Au-NPo array at the SPR condition, which was confirmed by the increase in the LCM Raman intensity.