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In the application of WS2 as a surface–enhanced Raman scattering (SERS) substrate, enhancing the charge transfer (CT) opportunity between WS2 and analyte is an important issue for SERS efficiency. In this study, we deposited few-layer WS2 (2–3 layers) on GaN and sapphire substrates with different bandgap characteristics to form heterojunctions using a chemical vapor deposition. Compared with sapphire, we found that using GaN as a substrate for WS2 can effectively enhance the SERS signal, with an enhancement factor of 6.45 × 104 and a limit of detection of 5 × 10−6 M for probe molecule Rhodamine 6G according to SERS measurement. Analysis of Raman, Raman mapping, atomic force microscopy, and SERS mechanism revealed that The SERS efficiency increased despite the lower quality of the WS2 films on GaN compared to those on sapphire, as a result of the increased number of transition pathways present in the interface between WS2 and GaN. These carrier transition pathways could increase the opportunity for CT, thus enhancing the SERS signal. The WS2/GaN heterostructure proposed in this study can serve as a reference for enhancing SERS efficiency.

Despite the use of transition metal dichalcogenides being widespread in various applications, the knowledge and applications of MoxW1−xS2 compounds are relatively limited. In this study, we deposited a MoW alloy on a Si substrate using a sputter system. Consequently, we successfully utilized a furnace to sulfurize the MoW alloy from 800 to 950 °C, which transferred the alloy into a MoxW1−xS2 ternary compound. The Raman spectra of the MoxW1−xS2 samples indicated an additional hybridized Raman peak at 375 cm−1 not present in typical MoS2 and WS2. With increasing sulfurization temperature, the scanning electron microscopy images revealed the surface morphology of the MoxW1−xS2 gradually becoming a sheet-like structure. The X-ray diffraction results showed that the crystal structure of the MoxW1−xS2 tended toward a preferable (002) crystal orientation. The I–V results showed that the resistance of MoxW1−xS2 increased when the samples were sulfurized at a higher temperature due to the more porous structures generated within the thin film. Furthermore, a high-temperature coefficient of resistance for the MoxW1−xS2 thin film sulfurized at 950 °C was about −1.633%/K−1. This coefficient of resistance in a MoxW1−xS2 thin film indicates its suitability for use in thermal sensors.