The role of annealing temperature on the structure and optical properties of nanostructured Au-NP aligned TiO₂-NW

In this work, we synthesized the TiO₂ nanowire (NW) and Gold (Au) nanoparticle (NP) aligned TiO₂-NW using glancing angle deposition (GLAD) associated with e-beam evaporation technique. Further, synthesized samples annealed at 400 °C, 600 °C, and 900 °C to change crystallite nature of material. The presence of anatase phase has more percentage than rutile phase till 600 °C, while annealed at 900 °C most of phase transformed into rutile phase. XRD and Raman’s spectra verified the annealing temperature phase transition. The effect of surface plasmon resonance (SPR) of Au-NP was observed in optical absorption and photoluminescence (PL) spectra. Moreover, anatase-rutile phase exhibited enhanced optical absorption. The bandgap decreases and crystallite size increases while increasing value of annealing temperature. The field emission scanning electron microscope (FESEM) images confirm the formation of TiO₂-NW along with Au-NP on Si substrate. The average length and diameter of TiO₂-NW were ⁓230 nm and ⁓54 nm, respectively. It was noted that the diameter of the Au-NPs varied, ranging from ⁓5 nm to ⁓10 nm. This phase transformation investigation will ultimately aid in the optimization of synthesis processes in numerous photo activity related applications. The common potential applications are photocatalysis, gas sensors, photovoltaics, memory and biomedical applications.