The Effect of Geometric Structure on Photoluminescence Characteristics of 1-D TiO₂Nanotubes and 2-D TiO₂Films Fabricated by Atomic Layer Deposition

TiO 2 thin films and TiO 2 nanotube arrays were fabricated on Si and quartz substrates by atomic layer deposition (ALD) with the application of anodic aluminum oxide (AAO) template at 400°C. In particular, the thickness of the film and the wall thickness of the nanotubes can be controlled precisely using ALD technique. The photoluminescence (PL) characteristic of TiO 2 thin films was improved with increased thickness. However, for TiO 2 nanotube arrays, with the decrease of the wall thickness, higher PL intensity was obtained. Compared TiO 2 thin film with TiO 2 nanotube arrays, TiO 2 nanotube arrays exhibited a better performance on PL characteristic due to larger surface area. Owing to larger amount of oxygen vacancies on the surface, compared with the volume factor, surface area was a more important factor that affected the performance of PL characteristics. Therefore, when the volume of TiO 2 nanotube arrays became smaller, the ratio of surface area to volume was increased and the influence from the surface area became the dominating factor on the performance of the PL characteristics.