The effect of carrier gas flow on structural and optical properties of TiO2 nanowires

Optical properties and photoluminescence of TiO2 nanowires, synthesized by two-step thermal evaporation process, under different Ar gas flow as carrier have been studied. The gas flow was varied from 50 to 150 sccm in order to find the optimum gas flow to growth TiO2 nanowires. As evidenced by X-ray diffraction patterns, our synthesized nanowires, were found to be crystalline rutile TiO2. Our results indicated a convenient gas flow for controlling diameter size of nanowires was about 100 sccm. In this case, diameters and lengths were, respectively, within the ranges of 40–100 and 400–1800 nm. The experimental data of the reflectance of TiO2 nanowires have been obtained through using spectrometer of wavelength 250–800 nm that has been indicated reflectance decreasing with increasing the gas flow, due to the scattering from the surface of the nanowires and also an increase in voids’ roughness. Under excitation 370 nm, the TiO2 nanowires can emit light peaked at 435 nm. It is believed that peak 435 may be due to free excitons emission.