Characterization of Single-Crystalline TiO2 Nanowires Grown by Thermal Evaporation

Abstract

Single-crystalline nanowires (NWs) were grown all over a (Si) substrate by thermal evaporation using a radio frequency heater. The 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 . The X-ray diffraction pattern indicates that the NWs are composed of the rutile phase. 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 NWs to be synthesized. The luminescence characteristics and the doping effect of NWs were studied by cathodoluminescence (CL) in FESEM at room temperature. The CL spectra revealed a broad blue band of (3.08 eV) for undoped NWs and one of 439 nm (2.82 eV) for n-doped NWs, respectively.