Preparation and photoluminescence of highly ordered TiO2 nanowire arrays

Highly ordered TiO2 nanowire (TN) arrays were prepared in anodic alumina me mbranes (AAMs) by a sol-gel method. The TNs are single crystalline anatase phase with uniform diameters around 60 nm. At room temperature, photolumine scence (PL) measurements of the TN arrays show a visible broadband with thr ee peaks, which are located at about 425, 465, and 525 nm that are attribut ed to self-trapped excitons, F, and F+ centers, respectively. A model is al so presented to explain the PL intensity drop-down of the TN arrays embedde d in AAMs: the blue PL band of AAMs arises from the F+ centers on the pore walls, and the TNs first form in the center area of the pores and then exte nd to the pore walls. (C) 2001 American Institute of Physics.