# A High-Performance Thin-Film Sensor in 6G for Remote Sensing of the Sea Surface
## 2 Experimental Design  
Figure 1 shows the experimental setup used in our study. In order to produce high-quality Te films, a two-step process was followed. Initially, Te films were deposited onto silicon substrates using magnetron sputtering. Subsequently, the devices were transferred to an annealing table shielded by nitrogen gas. These devices were then heated to various temperatures and held for different durations to complete the annealing process. Finally, the Raman spectra of the samples were analyzed under different annealing conditions to assess the quality of the annealing process. The prepared film area was 20 mm \(\times\) 20 mm. The Te film was prepared using the following steps. At first, the air pressure was reduced to 1 \(\times\) 10\({}^{-5}\) Pa, and argon was injected into the cavity. The Te target was coated using RF drive mode, and the parameters were set as follows. An argon flow rate of 30 SCCM, power of 180 W, and duration time of 1200 s were used. These coating parameters were optimized for the process. Then, Raman spectra were measured for the different Te films. The Raman signal of a sample is commonly used to characterize the degree of crystallization and stress. In a pure lattice, the vibrational energy of the lattice is more concentrated, resulting in a  
Figure 1: Experimental setup diagram. (**a**) Microcurrent testing probe platform; (**b**) THz time-domain spectrometer. narrow spectral peak width. Conversely, if the lattice is damaged or poorly crystallized, the vibrational energy after excitation spreads over a wider range, leading to a broadened spectral peak width. When the lattice is subjected to compression or stretching without being destroyed, stress is generated, which is manifested as a peak displacement. Therefore, the intensity and width of the Raman peak are typically used to determine the degree of crystallization of the fabricated film. A higher peak intensity and narrower peak width correspond to stronger crystallization of the sample. It can be concluded that the Te films exhibit optimal crystallinity when annealed at a temperature of 100 \({}^{\circ}\)C for 30 min. The degree of crystallization decreases when the energy provided to Te is insufficient or excessive, either without annealing or when the annealing temperature exceeds 100 \({}^{\circ}\)C.  
Furthermore, the polarization Raman results were also measured at different annealing temperatures. The laser incident on the sample with varying polarization directions exhibited distinct polarization characteristics. The formation of a polarization sheet-like effect by the main atomic chain was more pronounced in films with higher crystallization degrees, indicating a higher polarization degree of polarization Raman. The highest polarization was observed at an annealing temperature of 100 \({}^{\circ}\)C, as determined by analyzing the peak results [34; 35]. In addition, the analog degree of polarization (_DOP_) was defined to calculate the polarization sensitivity of the device [36]:  
\[DOP=\left|\frac{M_{\text{max}}-M_{\text{min}}}{M_{\text{max}}+M_{\text{min}}}\right| \tag{1}\]  
where \(M_{\text{max}}\) and \(M_{\text{min}}\) are the maximum and minimum Raman intensities, which are parallel and perpendicular to the polarization direction of the laser, respectively. According to Equation (5), the maximum _DOP_ of the device was 0.19, 0.16, and 0.13. It can be seen that the degree of crystallization of the sample annealed at 100 \({}^{\circ}\)C was better than that of the non-annealed sample and the sample annealed at 200 \({}^{\circ}\)C. The polarization Raman experiments provided clear evidence of the enhanced crystallization of Te films annealed at 100 \({}^{\circ}\)C.  
The Raman spectroscopy results and scanning electron microscopy (SEM) images of the Te thin films are presented in Figure 2. The film thickness was determined using the SEM analysis of the cut surface.