XRD and XPS Analysis of TiO2 Thin Films Annealed in Different Environments (original) (raw)
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Effect of thermal annealing on the structure and microstructure of TiO 2 thin films
Indian Journal of …, 2009
Nanostructured TiO 2 thin films have been prepared through chemical route using sol-gel and spin coating techniques. The deposited films were annealed in the temperature range 400-1000°C for 1 h. The structure and microstructure of the annealed films were characterized by GAXRD, micro-Raman spectroscopy and AFM. The as-deposited TiO 2 thin films are found to be amorphous. Micro-Raman and GAXRD results confirm the presence of the anatase phase and absence of the rutile phase for films annealed up to 700°C. The diffraction pattern of the film annealed at 800 to 1000°C contains peaks of both anatase and rutile reflections. The intensity of all peaks in micro-Raman and GAXRD patterns increased and their width (FWHM) decreased with increasing annealing temperature, demonstrating the improvement in the crystallinity of the annealed films. Phase transformation at higher annealing temperature involves a competition among three events such as : grain growth of anatase phase, conversion of anatase to rutile and grain growth of rutile phase. AFM image of the asdeposited films and annealed films indicated exponential grain growth at higher temperature.
Surface properties of doped and undoped TiO 2 thin films deposited by magnetron sputtering
Vacuum, 2009
In this work, transparent titanium dioxide (TiO 2 ) thin films were deposited onto microscope glass slides by means of the d.c. reactive magnetron sputtering method. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV-visible spectroscopy (UV) and contact angle analysis using the Owens-Wendt method for the surface energy calculation. The photocatalytic activity of the films was tested by measuring the photodegradation of Rhodamine-B (RhB) dye under radiation of UV light. Iron-doped TiO 2 films were also prepared in order to study the Fe-doping effect on TiO 2 photocatalytic activity. The influences of different iron concentrations on the contact angle of the series of Fe-doped TiO 2 thin films, were investigated. The influences of total sputtering pressures on TiO 2 photocatalytic activity were also investigated. It was observed that the photocatalytic activity of the TiO 2 thin films was slightly improved by increasing the total sputtering pressure. Moreover, it was also observed that in general, iron-doping was detrimental for photocatalytic activity, nevertheless the films with low iron concentrations showed better photocatalytic activity than those with high iron concentrations. It was found that iron-doping has changed the wettability appetency of TiO 2 coated surfaces.
Materials Research Bulletin, 2016
A technique to deposit Nb-doped films of TiO 2 by radio-frequency magnetron sputtering was investigated. Nb wires are put onto the sputter track of a metallic titanium target and the oxidation state of the target is controlled by the intensity of a Ti line from the plasma emission. The sputtered films are analyzed with X-ray diffraction, RBS (Rutherford back scattering), energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and SEM (scanning electron microscopy). After post-heating at 400°C, all films exhibit the anatase structure. The films are polycrystalline with a Nb/[Nb + Ti] content from 2 to 17 at.%. RBS and SEM indicate that the films consist of two sub-layers with the surface layer containing more Nb and exhibiting a clearer columnar structure. There is an optimum oxidation state of the target in the transition region between metallic and oxidic modes where the lowest resistivity of 7 × 10 −4 Ωcm is achieved. Nb is incorporated as Nb 5+ into the anatase lattice, but in suboptimal films, Ti vacancies (acceptors) may compensate the donor effect of Nb. The oxygen content in the films is higher than for stoichiometric TiO 2. O interstitials may increase the mass density of the films. The lattice parameter a and the unit cell volume increase with the Nb content in a similar manner as observed for single crystals of TiO 2 :Nb.
Structural investigation and electronic band transitions of nanostructured TiO2 thin films
Crystal Research and Technology, 2011
Titanium dioxide (TiO 2) thin film was deposited on n-Si (100) substrate by reactive DC magnetron sputtering system at 250 °C temperature. The deposited film was thermally treated for 3 h in the range of 400-1000 °C by conventional thermal annealing (CTA) in air atmosphere. The effects of the annealing temperature on the structural and morphological properties of the films were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. XRD measurements show that the rutile phase is the dominant crystalline phase for the film annealed at 800 °C. According to AFM results, the increased grain sizes indicate that the annealing improves the crystalline quality of the TiO 2 film. In addition, the formation of the interfacial SiO 2 layer between TiO 2 film and Si substrate was evaluated by the transmittance spectra obtained with FTIR spectrometer. The electronic band transitions of as-deposited and annealed films were also studied by using photoluminescence (PL) spectroscopy at room temperature. The results show that the dislocation density and microstrain in the film were decreased by increasing annealing temperature for both anatase and rutile phases.
Characterization of TiO2 thin films deposited by using dc magnetron sputtering
2016
Titanium dioxide thin films were deposited on silicon (111) and glass substrates by using direct current (dc) magnetron sputtering system. Thin films were deposited with different O2 gas flow rate (1, 3, 9, 12 sccm) while keeping Ar gas flow rate constant at 30 sccm. The samples exhibit amorphous phase as deposited and become polycrystalline at 350oC. X-ray diffraction (XRD) studies confirmed existence of anatase and rutile phase after post deposition annealing. As deposited films were transparent and their band gap increases with increase in oxygen gas flow rate. Fourier transform infrared (FTIR) spectroscopy data confirmed the existence of Ti-O band present in deposited films.
Analyzing the Development of N-Doped TiO2 Thin Films Deposited by RF Magnetron Sputtering
Sensor Letters, 2013
The aim of this experiment was the improvement of TiO 2 thin films properties by N-doping using RF magnetron sputtering, followed by an annealing process. The surface elemental composition and electronic structure, film crystallinity and optical properties were investigated by means of X-ray and valence band photoelectron spectroscopy, X-ray diffraction and UV-Vis spectrophotometry. The nitrogen content of the as-deposited films could be adjusted up to 4.1 at% but, it decreases dramatically after the thermal treatment. Transition from amorphous to crystalline structure was induced by successive annealing. The band gap of the deposited materials becomes narrower due to nitrogen doping and TiO 2 rutile phase formation.
MRS Proceedings, 2002
ABSTRACTAnatase (A), rutile (R) and amorphous phase TiO2 thin films have been prepared by RF magnetron sputtering on unheated glass substrates by controlling the total pressure of sputtering gases (Ar + O2) and the substrate bias. The crystal structures of the films were confirmed by x-ray diffraction and Raman scattering. The analysis of optical absorption data for A- TiO2 film shows an energy bandgap (Eg) of 3.2 eV (indirect extrapolation) and ∼ 3.5 eV (direct extrapolation). On the other hand, R-TiO2 film shows Eg ∼ 2.9 eV (indirect) and 3.2 eV (direct). The latter film also shows the presence of amorphous regions with Eg ∼ 3.0 eV (indirect) and 3.8 eV (direct). The bandgap of both the films, obtained using indirect extrapolation, has a value range consistent with the previous measurements.
2007
The effect of sodium content of the glass support on the crystallinity of sputtered TiO 2 films and photocatalytic breakdown of ethanol has been studied. It was found that the activity of the as-deposited (amorphous) films does not depend on the type of support used. The chemical composition of the glass support does influence the activity of annealed films. When using soda-lime glass support sodium diffuses into the film upon annealing, suppressing anatase crystallization and decreasing its photocatalytic activity. To decrease the influence of sodium, soda-lime glass coated with an e-beam evaporated SiO 2 barrier layer was used with good result. A reduced sodium concentration in the film leads to well crystallized anatase after annealing. An increased photocatalytic activity was observed for these films.
2014
Titanium dioxide gas sensors are typically employing metastable anatase nanocrystalline phase. Operation at high temperature can thus negatively affect their long term stability. Employment of rutile phase with strong texture and larger grain size may ensure better reliability and longer lifetime. Therefore in this work we study the possibility to utilize stable rutile phase thin films prepared at relatively low temperature on c-cut sapphire substrates. Technological conditions have been chosen in order to obtain highly oriented titanium dioxide rutile thin films using reactive DC magnetron sputtering on unheated substrates. Subsequent ex-situ annealing in temperature range from 500°C to 800°C leads to increase of crystallite size and improvement of in-plane preferential orientation. Surface topography has been characterized by atomic force microscopy. Structure, texture and the strain evolution has been investigated using x-ray diffraction measurements. All investigated thin films showed epitaxial relationship with respect to the substrate: rutile-TiO 2 (100)[001] || Al 2 O 3 (0001)[1 1 00]. Sensitivity of such rutile films to hydrogen has been measured and compared with our previous results on anatase thin films.