## 3 Results and Discussion
### Structural Characterization  
Figure 5 shows the results from the XRD analysis of all three types of samples of CdTe thin films evaporated or sputtered onto optical glass or electrodeposited onto Au-coated Si substrate, respectively. The crystallographic texture observed from the structural investigation is provided by the strong preferential orientation of the (111) diffraction plane, regardless of the choice of deposition method. For CdTe layers prepared by VTE (Figure 5a) and RF-MS (Figure 5b), only the CdTe phase was detected. In contrast, the electrodeposited CdTe film (Figure 5c) presents an additional structural phase of Cd. As previously mentioned, in addition to the direct influence of the deposition parameters on CdTe thin films properties, it is important to carefully optimize the synthesis process by taking into consideration different Cd:Te atomic ratios in the electrolytic solution with respect to the other variables in the electrochemical process. Notably, the CdTe \"zinc blend\"-type structure retains its preferential orientation and no separated phase of Te was highlighted in the XRD measurement, in contrast to the crystallization of metallic Cd. Finally, the strong signal of the Au (111) diffraction plane from Figure 5c is related to the Au-coated Si substrate employed in the preparation of CdTe by ECD. Figure 5: X-ray diffraction (XRD) characterization of CdTe thin films deposited by VTE (**a**), RF-MS (**b**), and ECD (**c**). VTE and RF-MS thin film control samples were prepared using pristine optical glass substrates, while ECD test samples were synthesized using a common Au-coated Si substrate. The XRD data recorded in symmetric theta-theta geometry around the CdTe (111) crystalline plane are presented in Figure 6 together with the theoretical curves obtained by fitting the experimental data with a Voigt profile [13; 40; 41]. The residual of the fit procedure is shown at the bottom of each graph. The Voigt profile provides information on the integral breadths of the Gauss and Lorentz components, which can be used further to calculate the mean-square micro-strain and crystallite size, respectively (see Table 2). By comparison, the values of the mean square strain, i.e., \(\langle\epsilon^{2}\rangle^{1/2}\), of CdTe layers deposited by VTE and RF-MS are almost identical, while the CdTe thin film prepared via the VTE method exhibits a larger crystallite size (Deff). For the ECD-prepared CdTe thin film, the smaller value of crystallite size and higher micro-strain value is caused by the more energetic processes at the working electrode interface during the ECD process, which lead to fast growth of lower crystallinity films. Thus, the low surface mobility which is present in the electrochemical preparation of the CdTe leads to a slight deviation from the structural and morphological characteristics of the CdTe layers synthesized by VTE or RF-MS. Moreover, the differences in stoichiometry of the compound are partly responsible for the higher mechanical stress observed in the structure of the CdTe film obtain by ECD. However, another feature that may stand for the unsuccessfully attempts in covering and penetrating the Cu NW matrix by evaporating or sputtering CdTe is the Deff values of the thin films. Because the VTE and RF-MS deposition methods promote the growth of larger crystallites (81 nm and 64 nm, respectively), it is highly probable that Cd and Te atoms condense first on the tips of the Cu NWs featuring an average diameter of about 90 nm and an average center-to-center distance around 150 nm. Thus, in a very short time a thin CdTe film forms on top of the dense vertical array of Cu NWs, while the space between Cu NWs remains empty. Overall, the experimental values for the lattice constant (a) of CdTe prepared by VTE, RF-MS, and ECD have small variation from that of the bulk CdTe crystal [42] due to the mechanical stress, as shown by the micro-structural parameters presented in Table 2.