Recently, extraordinary physical properties of two-dimensional transition metal dichalcogenides (TMDs) have attracted great attention for various device applications, including photodetectors, field effect transistors, and chemical sensors. There have been intensive research efforts to grow high-quality and large area TMD thin films, and chemical vapor deposition (CVD) techniques enable scalable growth of layered MoS2 films. We investigated the roles of Au nanoparticles (NPs) on the transport and photoresponse of the CVD-grown MoS2 thin films. The Au NPs increased conductivity and enabled fast photoresponse of MoS2 thin films. These results showed that decoration of metal NPs were useful means to tailor the physical properties of CVD-grown MoS2 thin films. To clarify the roles of the metal particles, we compared the transport characteristics of MoS2 thin films with and without the Au NPs in different gas ambient conditions (N2, O2, and H2/N2). The ambient-dependence of the MoS2 thin films allowed us to discuss possible scenarios to explain our results based on considerations of band bending near the Au NPs, gas adsorption/desorption and subsequent charge transfer, and charge scattering/trapping by defect states.
We report new 3D hybrid plasmonic nanostructures exhibiting highly sensitive SERS-based sensing performance,
utilizing efficient plasmonic light absorption and analyte-enrichment effect. The hybrid plasmonic nanostructures
composed of 3D-stacked Ag NWs and NPs separated by a thin hydrophobic dielectric interlayer. A hydrophobic
polydimethylsiloxane (PDMS) interlayer provides dielectric nanogap between Ag NWs and NPs, and analyte-enrichment
effect due to the inhibition of drop spreading. The 3D hybrid PDMS-interlayered Ag nanostructures showed
hydrophobicity with initial contact angle of 137.6°. Utilizing the analyte-enrichment strategy, the PDMS-interlayered Ag
nanostructures exhibited an enhanced sensitivity of methylene blue molecules by a factor of 10 (limit of detection, LOD
of 1.5 nM), compared to the alumina-separated 3D hybrid Ag nanostructures.