## 3 Results
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Target** & **Power Type** & \begin{tabular}{c} **Contact Angle** \\ **(deg.)** \\ \end{tabular} & \
\begin{tabular}{c} **Sheet Resistance** \\ **(\(\Omega\)/sq)** \\ \end{tabular} &
\begin{tabular}{c} **Transmittance** \\ **(\%)** \\ \end{tabular} & **b*** \\ \hline Pure PTFE & RF & 109.83 \(\pm\) 0.42 & over & 90.56 \(\pm\) 0.27 & 0.69 \(\pm\) 0.06 \\ \hline Cu 20/PTFE 80 & RF & 100.34 \(\pm\) 0.33 & over & 89.92 \(\pm\) 0.29 & 1.31 \(\pm\) 0.04 \\ \hline Cu 50/PTFE 50 & RF & 95.85 \(\pm\) 0.44 & over & 89.49 \(\pm\) 0.32 & 1.37 \(\pm\) 0.04 \\ \hline Cu 80/PTFE 20 & RF & 76.67 \(\pm\) 0.19 & over & 64.80 \(\pm\) 0.33 & 14.30 \(\pm\) 0.08 \\ \hline Cu 80/PTFE 20 & MF & 12.10 \(\pm\) 0.48 & 2.00 \(\pm\) 0.21 (\(\times 10^{4}\)) & 15.68 \(\pm\) 0.21 & 22.39 \(\pm\) 0.15 \\ \hline Cu 80/PTFE 20 & DC & 48.31 \(\pm\) 0.33 & 34.55 \(\pm\) 1.40 & 5.62 \(\pm\) 0.11 & 6.48 \(\pm\) 0.05 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Properties of Cu/PPFC nanocomposite thin films using Cu/PTFE composite targets. b*—yellow index. Figure 4: Optical transmittance at 500 nm for different Cu contents and power sources. The chemical structure of the Cu/PPFC nanocomposite thin films was analyzed by XPS. The intensity of the binding energy was calibrated based on the position of the C-C bond (sp\({}^{3}\) hybrid orbital, 284.8 eV). Figure 6a shows the normalized C 1s core-level XPS spectra of the Cu/PPFC nanocomposite thin films prepared by RF sputtering of the Cu/PTFE composite target. The C 1s spectra exhibit broad Gaussian deconvolution peaks that have the following customary assignments for a fluorocarbon thin film: 294.0 eV (CF\({}_{3}\)), 292.0 eV (CF\({}_{2}\)), 289.8 eV (CF), 287.5 eV (C-CF\({}_{n}\)), and an additional C=O peak at 288.6 eV owing to binding with oxygen [16; 31; 34]. The intensity of the CF\({}_{2}\) bond, which is typical in a fluorocarbon thin film, is decreased owing to the low fluorine bonding ratio and high carbon bonding ratio in the thin film with increasing Cu content. In the Cu 80 RF thin film, the composition ratio of fluorine was drastically decreased, and most of the bonds were formed between carbon and oxygen (C=O) upon exposure of the thin film to air. In the Cu 80 RF thin film, the bonding ratio of fluorine decreased sharply, and the bond between carbon and oxygen (C=O) appeared after air exposure of the thin film. Figure 6b shows that the C 1s core-level spectra of the Cu 80 RF, Cu 80 MF, and Cu 80 DC thin films have no binding energy peaks due to the CF\({}_{2}\) bond, and that the carbon bond is dominant. The Cu 2p spectra of the Cu/PPFC nanocomposite thin films are shown in Figure 6c. The Cu 20 RF and Cu 50 RF thin films showed almost no binding energy peak, whereas the Cu 80 RF, Cu 80 MF, and Cu 80 DC thin films showed Cu 2p\({}_{3/2}\) binding energy peaks at 932.7 eV and a Cu 2p\({}_{1/2}\) binding energy peak at 952.6 eV (\(\Delta\)BE = 19.9 eV) [12]. In the Cu 80 RF thin film, CuCO\({}_{3}\) binding energy peaks were observed at 934.6 eV (Cu 2p\({}_{3/2}\)) and 954.5 eV (Cu 2p\({}_{3/2}\)), which is presumably due to surface oxidation after thin film fabrication. A shake-up satellite peak of Cu\({}^{2+}\) [Ar] 3d\({}^{9}\) orbital configuration was observed in the binding energy range of 938.5-946.0 eV (Cu 2p\({}_{3/2}\)) and 959.0-965 eV (Cu 2p\({}_{1/2}\)). Shake-up satellite peaks appear strongly when Cu is oxidized to form CuO or CuF\({}_{2}\). Thus, the Cu 80 DC thin film exhibits excellent conductivity, a large crystal size of Cu, as well as a low oxidation degree. Figure 6d shows the chemical quantification results, obtained by considering the relative sensitivity factors of each binding energy peak in the XPS spectra.