Characteristics of Aligned Aluminum-Doped Zinc oxide nanorod arrays via a novel sonicated sol-gel immersion

Aligned Aluminum (Al)-doped zinc oxide (ZnO) nanorod arrays were prepared on seeded catalyst-coated glass substrates using a novel technique of sonicated sol-gel immersion method at different annealing temperatures. The diameter sizes of synthesized hexagonal-shaped nanorods are found to be in the range between 50 nm to 150 nm. The annealing treatment up to 500 °C did not give any significance effects on the nanorods morphology as observed by field emission scanning electron microscopy (FESEM). The micro-Raman spectra reveal that the crystallinity of the nanorod arrays were improved at higher annealing temperature as shown by the E2 (high) peak intensity enhancement. This result was supported by XRD spectra where the XRD peak intensity for annealed nanorods is higher than as-grown nanorods. XRD spectra reveal Al-doped ZnO nanorod arrays grew preferentially along the (002) plane or the c-axis, indicating high quality of the ZnO crystal. Al forms Ohmic contacts with Al-doped ZnO nanorod arrays that are shown through a linear current-voltage (I-V) characteristic. The conductivity of nanorod arrays increased with annealing temperatures up to 500 °C with a maximum conductivity ~1.72 × 10-2 Scm-1.