Sulfur (S)-doped titanium dioxide (TiO2) was synthesized by ion implantation and subsequent thermal annealing. The S ions were implanted into the single crystals of rutile TiO2 at a fluence of 8×1015 ions/cm2. According to the results of Rutherford backscattering spectroscopy and ion channeling analysis, the irradiation damage recovered by annealing at 600 °C in air. In the annealed crystal, the S atoms occupied oxygen sites for form Ti-S bonds, as confirmed by x-ray photoelectron spectroscopy. Compared to the pure TiO2, a photocurrent was observed in the lower-energy regions for the S-doped TiO2. Based on the theoretical analyses by the first-principles band calculations using the full potential linearized augmented plane-wave methods within the generalized gradient approximation, the mixing of the S 3p states with the valence band (VB) was found to contribute to the increasing width of the VB. This leads to the band gap narrowing in the S-doped TiO2. Therefore, the photon-to-carrier conversion was induced during irradiation by visible light above 420 nm (<2.9 eV).

No abstract

No abstract

No abstract

Molybdenum (Mo) doped vanadium dioxide thin films were synthesized using a Mo striped vanadium (V) target during pulsed laser ablation process. The film structure was characterized by high resolution x-ray diffraction, x-ray rocking curve and Rutherford backscattering/channeling measurements. The results show that the full width at half magnitude of the x-ray rocking curve is as narrow as 0.0074°, comparable to that of the (0001) sapphire substrate, 0.0042°, in this study. The ratio of the aligned-to-random backscattered yield reaches 5%, implying that the growth is that of the single crystalline epitaxy. The result of angular scans for both V and Mo atomic channelings reveals that Mo atoms successfully take sites of the V sublattice as a substitutional dopant. It has been noted that the degradation of the phase transition properties of the film upon doping is closely related to the conductivity in the semiconductor phase.