Anodic formation of highly ordered TiO2 nanotube arrays on conducting glass substrate: Effect of titanium film thickness

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Highly ordered TiO2 nanotube arrays were successfully fabricated using ammonium fluoride electrolyte by galvanostatic anodization technique. The nanotube arrays were grown perpendicular to the titanium film deposited onto conducting glass substrate. The effect of the different titanium film thicknesses on the morphology, optical, and electrical properties of TiO2 nanotube arrays is investigated. It is found that the titanium film thickness is a crucial parameter for achieving highly ordered TiO2 nanotube arrays. Morphological investigations on the nanotube arrays reveal that anodization of 1.5 μm thick titanium films leads to formation of pores at the upper layer of the film with nonuniform pore size distribution and poor interconnectivity. Instead, anodization of 2.5 and 2.0 μm thick titanium films with the same conditions leads to formation of highly ordered TiO2 nanotube arrays with uniform size and sharp clear tubular structures, which are well connected to each other. The absorbance and optical band gap of the TiO2 nanotube arrays are also inferred from the diffuse reflectance spectra.Highly ordered TiO2 nanotube arrays were successfully fabricated using ammonium fluoride electrolyte by galvanostatic anodization technique. The nanotube arrays were grown perpendicular to the titanium film deposited onto conducting glass substrate. The effect of the different titanium film thicknesses on the morphology, optical, and electrical properties of TiO2 nanotube arrays is investigated. It is found that the titanium film thickness is a crucial parameter for achieving highly ordered TiO2 nanotube arrays. Morphological investigations on the nanotube arrays reveal that anodization of 1.5 μm thick titanium films leads to formation of pores at the upper layer of the film with nonuniform pore size distribution and poor interconnectivity. Instead, anodization of 2.5 and 2.0 μm thick titanium films with the same conditions leads to formation of highly ordered TiO2 nanotube arrays with uniform size and sharp clear tubular structures, which are well connected to each other. The absorbance and optical band ...