STRUCTURAL AND OPTICAL PROPERTIES OF NANO STRUCTURED TiO 2 THIN FILMS PREPARED BY SOL-GEL SPIN COATING TECHNIQUE (original) (raw)
Related papers
Structural and optical properties of TiO2 thin films prepared by spin coating
Abstract Transparent semiconducting thin films of titanium oxide (TiO2) were deposited on glass substrates by the sol–gel method and spin-coating technique. The phys- ical properties of the prepared films were studied as a function of the number of spun-cast layers. The micro- structure and surface orphology of the TiO2 films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), with respect to the film thickness. The XRD analysis reveals that the films are polycrystalline with an anatase crystal structure and a preferred grain orienta- tion in the (101) direction. The morphological properties were investigated by AFM, which shows a porous mor- phology structure for the films. The optical properties of the films were characterized by UV–Visible spectropho- tometry, which shows that the films are highly transparent in the visible region and their transparency is slightly influenced by the film thickness, with an average value above 80 %. The dependence of the refractive index (n), extinction coefficient (k), and absorption coefficient (a) of the films on the wavelength was investigated. A shift in the optical band gap energy of the films from 3.75 to 3.54 eV, as a function of the film thickness, has been observed.
Structural and optical properties of TiO2 thin films derived by sol–gel dip coating process
Journal of Non-Crystalline Solids, 2007
Nanocrystalline thin films of titanium dioxide have been fabricated on glass and silica substrates from partially hydrolyzed precursor solution. These films were subjected to heat treatment for 1 h at temperatures 100, 200, 300, 400, 500, 600, 700, 800 and 900°C and characterized by XRD, SEM, XPS and optical techniques. As deposited films are found to be amorphous and also contain hydroxyl and organic functional groups. Films heat treated above 100°C do not contain hydroxyl and organic functional groups. Microcrystalline behavior is observed in the films heat treated above 300°C. Crystallite size increases from $5 to 50 nm as sintering temperature is increased from 300 to 700°C. Formation of anatase phase with c-axis length 7.03 Å is observed in the films annealed up to 700°C. These films peel off from the substrate beyond 700°C annealing temperature. Density as well as refractive index of the films increases with increase in annealing temperature up to 700°C. Refractive index is found to show Cauchys behavior. Transmission better than 70% is observed in the visible range. There is a strong absorption around 370 nm, which is attributed to band gap absorption of the material.
Study on fabrication of TiO2 thin films by spin – coating and their optical properties
2016
Study on fabrication of TiO2 thin films and their optical properties in UV-VIS spectrum has been conducted. TiO2 nanopowders were prepared by co-precipitation method with varying mixing duration for 5, 10 and 25 hours using TiCl3 as precursor. The as-synthesized TiO2 phase is anatase having crystalline size of 14.25 nm, 13.75 nm and 12.62, respectively for the corresponding mixing duration. Thin films of TiO2 were fabricated by spin coating method and then checked by XRD diffractometer and UV-Vis Spectrophotometer to examine their structure and band gap energy. The prepared films also contain anatase phase of TiO2 with respective band gap of 3.70 eV, 3.74 eV and 3.76 eV, depending on the powders and their treatment.
Effect of Concentration Variation on Optical and Structural Properties of TiO2 Thin Films
Journal of Modern Materials, 2020
Concentrations in weight percent (5- 25 wt %) of TiO2 films used to optimize the film formation. The TiO2 films on glass substrates successfully obtained by spin-coating process using TiO2 nanopowder as precursor. Ultraviolet-Visible (UV-Vis), Scanning Electron Microscopy (SEM) equipped with Electron Diffraction X-ray (EDX) and X-ray Diffractometer (XRD) techniques used to characterize the films. The result of electron transport material (TiO2) showed that film prepared from 15 wt % of TiO2 solution and annealed at 450 has highest transmittance at visible light region with indirect optical band gap of 3.24 eV which corresponds to wavelength of 382 nm whereas 20 wt % has indirect band gap of 2.99 nm equivalent to 414.7 nm . The chemical analysis from Electron Diffraction Spectroscopy (EDS) of the material shows titanium and oxygen present at L and K-shells, respectively. The sample crystallized with preferred orientation at (101) from XRD analysis.
Journal of physics, 2019
The influence of thermal annealing to the properties of n-TiO2 thin films fabricated by sol-gel spin coating has been investigated using X-ray diffraction (X-RD) and UV-Vis optical transmittance measurements. TiO2 thin films were prepared by dissolving TiO2 Nanopowders into a solvent of ethanol and it becomes sol-gel. The sol-gel of TiO2 was deposited on indium tin oxide (ITO) substrate. Then, the TiO2 the thin films were inserted into tube furnace for annealing in the temperature range of 300 0 C to 500 0 C during 60 minutes. Based on the xray diffraction results, the crystal structure of TiO2 is anatase phase structures. The crystalline size of TiO2 films after annealing at 300 o C was 46.6 nm and it slightly decreased to 46.2 nm after annealing at 500 o C. The optical transmittance value of TiO2 film increased after annealing in comparison before annealing the TiO2 film.
Structural and Optical Properties of TiO2 Thin Films Prepared by Sol-Gel Process
Titanium oxide (TiO2) thin films were synthesized by sol–gel process: titanium tetraisopropoxide was dissolved in isopropanol, and then hydrolyzed by adding a water/isopropanol mixture with a controlled hydrolysis ratio. The resulting sol was deposited by “dip-coating” on a glass substrate with a controlled withdrawal speed. The obtained films were annealed at 350 and 500 oC (2 h). The structural, morphological and optical properties of the prepared films were analyzed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The Optical Waveguiding properties such as refractive index, thickness, number of propagating modes, and attenuation coefficient were measured at 632.8 nm by m-lines spectroscopy as a function of the elaboration parameters. The films exhibit diffraction pattern consistent with an anatase phase and the TiO2 planar waveguides are multimodes and demonstrate propagation losses as low as 0.3 dB/cm for annealing temperature 350 and 500 °C, respectively.
Journal of Scientific Research, 2016
The effect of annealing temperatures on the surface morphology and optical properties of titanium dioxide (TiO 2 ) thin films deposited by spin coating on Silicon substrate was studied. The TiO 2 thin films deposited onto silicon substrates were annealed at different temperatures. The structural and optical properties were studied using scanning electron microscopy (SEM), X-ray diffraction technique (XRD) and optical ellipsometer. The results indicated that the structural properties of the TiO 2 thin films were changed with the increase in annealing temperature. The SEM investigation showed that as annealing temperature was increased, the grain and pores size were increased. The XRD patterns of the studied samples showed that rutile phase were found in a sample annealed at high temperature. The ellipsometry investigation shows that the refractive index increased while energy band gap decreased with the annealing temperature. The results showed that surface porosity, optical properti...
2011
TiO 2 thin films were deposited on glass substrates by sol-gel method. Nanocrystalline TiO 2 thin films were prepared at ambient conditions and titanium tetraisopropoxide [C 12 H 28 O 4 Ti] was used as a Ti-precursor. The effect of annealing temperature on optical properties of nanocrystalline TiO 2 thin films was studied. The as-deposited films were dried at 100 0 C for 1 hr. The films formed were further heated in temperature between 200 and 500 0 C for 1 hr. The films were characterized by different techniques: XRD, UV-visible spectroscopy, FTIR spectroscopy and FESEM. The characterization studies revealed that the films are crystallized as anatase phase and nano-structured with better optical properties α = 0.89 as compared to reported data. The optical measurement showed the indirect band gap between 3.31 and 3.35 eV with corresponding crystallite sizes between 8.9 and 3.7 nm. The FESEM image of film annealed at 400 0 C showed spherical nanocrystalline structure of TiO 2 particles. The crystallite sizes obtained from FESEM image are found to be between 30 and 100 nm. It is also observed that refractive index of the film increases with increasing the annealing temperature. The smaller crystallite size gives larger band gap due to quantum size effects.
Applied Surface Science, 2010
Titanium dioxide thin films have been prepared from tetrabutyl-orthotitanate solution and methanol as a solvent by sol-gel dip coating technique. TiO 2 thin films prepared using a sol-gel process have been analyzed for different annealing temperatures. Structural properties in terms of crystal structure were investigated by Raman spectroscopy. The surface morphology and composition of the films were investigated by atomic force microscopy (AFM). The optical transmittance and reflectance spectra of TiO 2 thin films deposited on silicon substrate were also determined. Spectroscopic ellipsometry study was used to determine the annealing temperature effect on the optical properties and the optical gap of the TiO 2 thin films. The results show that the TiO 2 thin films crystallize in anatase phase between 400 and 800 • C, and into the anatase-rutile phase at 1000 • C, and further into the rutile phase at 1200 • C. We have found that the films consist of titanium dioxide nano-crystals. The AFM surface morphology results indicate that the particle size increases from 5 to 41 nm by increasing the annealing temperature. The TiO 2 thin films have high transparency in the visible range. For annealing temperatures between 1000 and 1400 • C, the transmittance of the films was reduced significantly in the wavelength range of 300-800 nm due to the change of crystallite phase and composition in the films. We have demonstrated as well the decrease of the optical band gap with the increase of the annealing temperature.
Journal of Materials Science: Materials in Electronics, 2013
The influence of the preparation conditions on the structural, morphological and optical properties of TiO2 thin films deposited on silicon substrate (Si), indium tin oxide coated glass (ITO) and alkali-free borosilicate glass (AFG), respectively is studied in this work. The X-ray diffraction analysis revealed that all TiO2 samples had a polycrystalline structure. The TiO2 films coated on Si showed a mixed phase of anatase and rutile while in the case of those on ITO and AFG only the pure anatase phase was observed. The crystallite size within the TiO2 thin films varied with the calcinations temperature, solvent lateral chain and catalyst type. The optical transmittance, band gap, reflective index and porosity were strongly affected by the annealing temperature, substrate nature and solvent.