The resistance and transmittance of Ti-oxide thin films sputtered on quartz substrates were studied. The electrical and optical properties can be changed by varying the percentage of O 2 introduced during the sputtering. The lowest resistivity for the sputtered Ti-oxide thin film was 2.30 × 10 -2 ω cm for 12.5% O 2, which was obtained after annealing at 400°C in ambient oxygen. The results of x-ray photoelectron spectroscopy (XPS) curve-fitting indicate that the Ti-oxide thin film contained both Ti 2O 3 and TiO 2 phases during deposition. The Ti 2O 3 phase was transformed into the stable TiO 2 phase during annealing. The Ti 2O 3-TiO 2 phase transformation initiated the substitution reaction. The substitution of Ti 4+ ions in the TiO 2 phase for the Ti 3+ ions in the Ti 2O 3 phase created the free electrons. This Ti 2O 3-TiO 2 phase transformation demonstrates the potential mechanism for conduction in the annealed Ti-oxide thin films. The transmittance of the annealed Ti-oxide thin films can be as high as approximately 90% at the 400 nm wavelength with the introduction of 16.5% O 2. This result indicates that the annealed Ti-oxide thin films are excellent candidates for use as transparent conducting layers for ultraviolet (UV) or near-UV light-emitting diode (LED) devices.
- oxygen vacancies
- phase transformation