## 3 Results and Discussion
The samples sulfurized below 850 \({}^{\circ}\)C exhibited a broad peak ranging from 20\({}^{\circ}\) to 40\({}^{\circ}\), which could be attributed to amorphous MoS\({}_{2}\) and poorly crystallized WS\({}_{2}\)[20; 21; 22]. This broad peak gradually disappeared when the sulfurized temperature was above 900 \({}^{\circ}\)C. As a result, the crystalline quality of Mo\({}_{\text{x}}\)W\({}_{1-x}\)S\({}_{2}\) thin film could be improved by means of  
Figure 1: Raman spectra of the Mo\({}_{\text{x}}\)W\({}_{1-x}\)S\({}_{2}\) thin films by sulfurizing MoW alloy at different temperatures from 800 to 950 \({}^{\circ}\)C.  
adjustment to the sulfurized temperature, which is consistent with the SEM observations. We initially determined the sulfurization mechanism in terms of our SEM and XRD results as follows: When the MoW alloy was sulfurized at a low temperature (below 850 \({}^{\circ}\)C), only some of the sulfur vapor reacted with the local MoW area, producing a few bumps, as shown in Figure 2a. At this stage, the sulfur atoms diffused into the layer in a disorderly pattern and reacted with Mo and W atoms, causing the amorphous structure and the poor crystal quality of the Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin film. Additionally, the increase in the thickness of the Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin film was limited. When the sulfurized temperature was increased to 850 \({}^{\circ}\)C, most sulfur atoms obtained enough energy to diffuse and react with the MoW alloy. Furthermore, the crystal quality improved, and the thickness of the Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin films increased. In comparison, the thickness of the Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin film sulfurized at 950 \({}^{\circ}\)C slightly reduced from 190 to 160 nm because of high-temperature conditions leading to the desorption effect. In addition, our results confirm that a well-crystallized Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin film was obtained when the MoW alloy was sulfurized at 950 \({}^{\circ}\)C. Because of the lattice mismatch between the Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin film and the substrate, the crystal orientation of Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin film produced high stress and strain. Once the stress relaxed, the Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin film separated from the substrate, as shown in the insert in Figure 2d. In order to understand the possibility of applying Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin films as thermal sensors, we measured the temperature-dependent I-V characteristics of our samples from 290 to 570 K, as shown in Figure 4a-d. The distance (ca. 5 mm) between the prepared electrodes was maintained as constant as possible for each sample. The I-V results show  
Figure 3: XRD 20 scan results of the Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin films sulfurized at various temperatures. Figure 2: SEM images of the Mo\({}_{\mathrm{x}}\)W\({}_{1-\mathrm{x}}\)S\({}_{2}\) thin films by sulfurizing MoW alloy at different temperatures: (**a**) 800, (**b**) 850, (**c**) 900, and (**d**) 950 \({}^{\circ}\)C. The insertion in each figure is the corresponding cross sectional SEM image. linear and ohmic measurements within \(-1\) to 1 V for each sample at various temperatures. The resistance trend for each sample was consistent with that of the semiconductor, decreasing with increasing measured temperature. The reason is that the electron absorbed the thermal energy when the temperature increased and further broke covalent bond to become a free electron. More and more free electrons were produced as the temperature increased, resulting in increased conduction and decreased resistance. According to [PERSON]'s law, we calculated the resistances in terms of the results in Figure 4a-d. The resistances of the samples measured at different temperatures are shown in Figure 5a.