Surface-enhanced Raman scattering for 2-D WSe₂ hybridized with functionalized gold nanoparticles.

Two-dimensional (2-D) transition metal dichalcogenides, such as MoS₂, WSe₂, and WS₂, are promising materials for application in field effect transistors, optoelectronics, and sensing devices. In this study, 2-D WSe₂ samples with various numbers of layers were hybridized with functionalized gold nanoparticles (Au-NPs) to achieve surface-enhanced Raman scattering (SERS). The nanoscale Raman and photoluminescence spectra of the WSe₂ layers and WSe₂/Au-NP hybrids were measured using a high-resolution laser confocal microscope. The WSe₂ exhibited distinct optical characteristics depending on the number of WSe₂ layers. The intensities of the Raman characteristic modes of the WSe₂ layers were significantly enhanced after hybridization with functionalized Au-NPs, indicating the SERS effect. The SERS effect weakened with increasing the number of WSe₂ layers. The SERS effect was more pronounced for mono- and bi-layer WSe₂ systems compared with the multi-layer WSe₂ systems.