Plasmonic interactions of gold nanoparticles with MoS₂-WS₂ Heterostructures

Scanning probe force microscopic techniques and optical spectroscopy have been widely used for sensing applications. Raman scattering and photoluminescence (PL) signals provide vital spectroscopic information about low vibrational modes and electronic properties of two-dimensional transition metal dichalcogenides (2D TMD). Since Raman signals are generally weak, chemical and electromagnetic mechanisms can enhance these signals using plasmonic materials such as gold nanoparticles (NPs) leading to surface-enhanced Raman scattering (SERS). The effects of the gold NPs deposited on lateral MoS₂-WS₂ heterostructures has been investigated using a combination of optical spectroscopic techniques. Changes in surface topography have been observed using atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), Tip-enhanced PL (TEPL) and Raman (TERS) spectroscopy. Contact potential difference obtained through KPFM has decreased as a result of high accumulation of gold NPs. Raman spectroscopy peak intensities have decreased, and PL peaks have been observed to become sharper and narrower which could be a result of the formation of surface cavities on TMD’s after the deposition of gold nanoparticles. This information can be applied to nano-optoelectronics and biosensing.