Single-crystalline TiO2 nanowires (NWs) were grown all over a TiO2/silicon (Si) substrate by thermal evaporation using a radio frequency heater. The TiO2 layer is experimentally determined to have better growing sites than the Si substrate. NWs were investigated by field-emission scanning electron microscopy (FESEM). The images showed NWs with uniform diameters of 60-90 nm and lengths of up to 3 mu m. The X-ray diffraction pattern indicates that the NWs are composed of the TiO2 rutile phase. TiO2 NWs were also examined using high-resolution transmission electron microscopy, which demonstrated that the NWs grew along the [110] axis as single crystalline. Adding nitrogen (N) during the growth process enabled n-doped TiO2 NWs to be synthesized. The luminescence characteristics and the doping effect of TiO2 NWs were studied by cathodoluminescence (CL) in FESEM at room temperature. The CL spectra revealed a broad blue band of similar to 402 nm (3.08 eV) for undoped NWs and one of 439 nm (2.82 eV) for n-doped NWs, respectively. (c) 2005 The Electrochemical Society. All rights reserved.