Synthesis, phase to phase deposition and characterization of rutile nanocrystalline titanium dioxide (TiO_2) thin films

摘要

In this work the preparation, deposition and structural properties of titanium oxide (TiO_2) thin films were investigated. The films were deposited by means of the e-beam physical vapor deposition (EBPVD) method in high vacuum (10~(-7)Torr). A controlled deposition rate in the range of 0.1-0.3A/s was monitored in situ employing quartz crystal. The films were deposited on the oxidized Si (100) wafer, glass micro slides. These films were analyzed using Grazing Angle X-ray diffraction (GA-XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RAMAN), Atomic Force Microscopy (AFM) and UV-visible Spectroscopy (UV-vis). Structural characterization results showed mainly presence of the crystalline rutile phase, however an interfacial SiO_2 layer between TiO_2 and the substrate and the minor anatase crystalline phase of TiO_2 was also identified in FTIR analysis. Grain size was found to be in the range of 100-125 nm while grain boundary was estimated to be 20 nm. Direct and indirect optical band gap was estimated to be 3.64 and 3.04 eV, respectively. A process induced self annealing of deposited film shows a strong effect on the structural, morphological and optical properties. Furthermore, low deposition rate and high vacuum allows rutile to rutile phase transformation from indigenously prepared TiO_2 target to thin film.