## 3 Results and Discussion  
The Raman spectra of the Mo\({}_{\rm x}\)W\({}_{1-x}\)S\({}_{2}\) thin films sulfurized at 800-950 \({}^{\circ}\)C are shown in Figure 1. All samples presented the same peak position with no obvious difference. The broad peak around 413 cm\({}^{-1}\) was created by the merging of two peaks: A\({}_{\rm 1g}\) mode at 405 cm\({}^{-1}\) for MoS\({}_{2}\) and A\({}_{\rm 1g}\) mode of 417 cm\({}^{-1}\) for WS\({}_{2}\), which are associated with the out-of-plane vibration frequency. The peak around 350 cm\({}^{-1}\) could be attributed to the in-plane vibration E\({}^{1}\)\({}_{\rm 2g}\) mode of WS\({}_{2}\). The above results are consistent with previously reported results [15,16]. However, there was a unique peak around 375 cm\({}^{-1}\) related to MoS\({}_{2}\), similar to that in the E\({}^{1}\)\({}_{\rm 2g}\) mode. [PERSON] et al. observed that the peak position of the MoS\({}_{2}\)-like E\({}^{1}\)\({}_{\rm 2g}\) mode shifted from 383 to 373 cm\({}^{-1}\) for the Mo\({}_{\rm x}\)W\({}_{1-x}\)S\({}_{2}\) hybrid triangle,suggesting that the MoS\({}_{2}\)-like E\({}^{1}\)\({}_{2g}\) mode could be attributed to local strain [17]. This phenomenon of mode shift was also found in uniform alloys of MoS\({}_{2}\) and WS\({}_{2}\) produced by chemical vapor transport [18]. Therefore, we inferred that mixing the two phases with different lattice constants resulted in the generation of the local strain when the Mo\({}_{\text{x}}\)W\({}_{1-x}\)S\({}_{2}\) thin film formed in our case, then the peak position of MoS\({}_{2}\)-like E\({}^{1}\)\({}_{2g}\) was encountered at around 375 cm\({}^{-1}\). However, the peak position of WS\({}_{2}\)-like E\({}^{1}\)\({}_{2g}\) at 350 cm\({}^{-1}\) does not shift even though the local strain exists [19]. Our Raman spectra results confirmed that our sulfurized conditions allowed the MoW alloy films to be completely sulfurized into the Mo\({}_{\text{x}}\)W\({}_{1-x}\)S\({}_{2}\) thin films because no peak correlating with the oxides of Mo or W elements could be found. Figure 2a-d shows the SEM images of the Mo\({}_{\text{x}}\)W\({}_{1-x}\)S\({}_{2}\) thin films after various sulfurized temperatures from 800 to 950 \({}^{\circ}\)C. For the sample sulfurized at 800 \({}^{\circ}\)C, Figure 2a reveals that there were some bumps swelling on the local area. In comparison, the morphology was highly consistent for the sample sulfurized at 850 \({}^{\circ}\)C in Figure 2b. For sulfurized temperature above 900 \({}^{\circ}\)C, Figure 2c presents the porous structure formed on the sample surface, and Figure 2d reveals the crystal feature had become more clearly visible. The insert images in Figure 2a-d provide information about the thicknesses after various sulfurization temperatures. The thickness was about 130 nm when the samples were sulfurized at 800 and 850 \({}^{\circ}\)C. The thickness reached 190 nm when the sulfurizing temperature was 900 \({}^{\circ}\)C and then decreased to 160 nm after sulfurizing the MoW alloy film at 950 \({}^{\circ}\)C. In addition, the Mo\({}_{\text{x}}\)W\({}_{1-x}\)S\({}_{2}\) thin film was partially separated from the substrate, as shown in the insert in Figure 2d. We provide a detailed discussion about the sulfurization mechanism below. We performed XRD on our samples in \(\omega\)-2\(\theta\) mode to confirm the crystal orientations and determined the sulfurization mechanism for the Mo\({}_{\text{x}}\)W\({}_{1-x}\)S\({}_{2}\) thin films under various sulfurized temperatures (see Figure 3). We thought that the present (002) peak was created by merging both MoS\({}_{2}\) and WS\({}_{2}\) (002) phases (JCPDS No. 24-0513 and JCPDS No. 08-0237, respectively). However, it was difficult to distinguish the X value of Mo composition for the Mo\({}_{\text{x}}\)W\({}_{1-x}\)S\({}_{2}\) thin film because the spacing along (002) for both MoS\({}_{2}\) and WS\({}_{2}\) were very close.