## 3 Results and Discussion
### Electrodeposition of ZnTe Nanowires Array into Nanochannel Templates  
Figure 7 shows the fabrication process of a zinc telluride nanowire array using a template electrodeposition technique [33; 34; 35; 36]. Ion-track etched polycarbonate nanochannel films (pore length of 6 \(\upmu\)m and pore diameter of 100 nm) and anodized aluminum oxide nanochannel films (pore length of 60 \(\upmu\)m and pore diameter of 200 nm) were used as nanochannel templates. One side of the filter was coated with sputter-deposited gold film to cover the nanochannels. This conductive gold layer acted as a cathode for the electrochemical growth of the zinc telluride nanowires. The zinc telluride nanowires were electrodeposited at the cathode potential range from \(-\)0.8 V to \(-\)1.4 V versus Ag/AgCl. After electrodepositing the zinc telluride nanowire array, the polycarbonate nanochannel films were dissolved in an organic solvent containing chloroform and dichloromethane, whereas the anodized aluminum oxide nanochannel films were dissolved in an aqueous solution containing 5N NaOH [37]. The remnant (zinc telluride nanowires) served as a sample to observe the nanostructure using SEM. Figure 8a shows the time dependence of the cathode current during the electrodeposition of the ZnTe nanowires in the anodized aluminum oxide (AAO) membranes. The effect of the cathode potential on the growth rate of ZnTe nanowires in AAO membranes was also shown in Figure 8b. As shown in Figure 8a, at the beginning of the electrodeposition within approximately 50 s, the cathode current decreased gradually with increasing the time. This phenomenon seems to be caused by the nucleation of ZnTe nanocrystals on the Au cathode and decreasing the concentration of the metal ions inside the AAO nanochannels. Following the initial nucleation stage, an almost constant cathode current was observed for a long time. For instance, the stable duration was approximately 1000 s at the cathode potential of \(-\)0.8 V while that was approximately 300 s at \(-\)1.4 V. During this second stage, ZnTe nanowires seemed to grow inside the AAO nanochannels at a constant growth rate. Finally, the cathode current increased rapidly due to the two-dimensional growth outside the AAO nanochannels on the template surface. The growth rate of ZnTe nanowires, \(R_{\text{g}}\) (nm/s), can be estimated from dividing the AAO nanochannel length, \(L\) (nm), by the nanochannel filling time, \(t\) (s). For example, \(R_{\text{g}}\) can be calculated to 5.54 nm/s (\(L\) = 60,000 nm and  
Figure 6: Effect of annealing temperature on the energy band gap (**a**) and resistivity (**b**) of electrodeposited ZnTe thin films onto ITO glass substrates. \(t=10,830\) s) at the cathode potential of \(-0.8\) V. As shown in Figure 8b, \(R_{\text{g}}\) increased with shifting the cathode potential to a less noble direction. This tendency corresponds well to the cathodic polarization curve (Tafel plot) as shown in Figure 1a. The stoichiometric composition was obtained at \(-0.8\) V while the zinc content in the deposit increased with an increase in the cathodic overpotential, as shown in Figure 1b. Figure 7: Fabrication process of ZnTe nanowires array using a template electrodeposition technique. Commercially available ion-track etched polycarbonate membrane filters were used as a nanochannel template. The aqueous electrolytic solution was synthesized from ZnSO4.7H2O (0.1 M), TeO2 (0.002 M), sodium sulfate (0.5 M), citric acid (0.05 M), and sodium citrate (0.05 M). The solution pH and temperature were set to ca. 4.0 and 313 K, respectively. Figure 9 shows the SEM images of the electrodeposited zinc telluride nanowire array. The nanochannel structures of the ion-track etched polycarbonate films (a) and anodized aluminum oxide films (b) were transferred precisely to the three-dimensional nanostructure of the zinc telluride nanowire array. The aspect ratio of the nanowires achieved up to approximately 300 which was obtained from the anodized aluminum oxide templates.