Papers by Keyword: TiO₂ Thin Films

Abstract: Titanium dioxide thin films were deposited by radio frequency sputtering on glass substrates at different substrate temperatures. Hence, we first optimized the preparation conditions and parameters which offer better control and reproducibility of film fabrication. Then, we investigate the structural, morphological and optical properties of the prepared titanium dioxide thin films. To do so, we used several characterization techniques: X-ray diffraction, Raman spectroscopy, scanning electron microscopy, atomic force microscopy and ultraviolet-visible spectroscopy. Interesting results were obtained, e.g. X-ray diffraction analysis shows that the films crystallize only in the anatase tetragonal structure with a preferential orientation along the (101) plane. The intensity of the (101) diffraction peak and the crystallite size are found to increase with increasing substrate temperature, indicating a crystallinity improvement of the films. Raman peaks observed around 144, 197, 399, 515 and 639 cm⁻¹ confirm that all samples possess anatase phase and the crystallinity is enhanced with increasing substrate temperatures. The analysis of scanning electron microscopy and atomic force microscopy images demonstrates that increasing the substrate temperature significantly affects the morphology, grain size and surface roughness of TiO₂ films. The ultraviolet-visible spectroscopy analysis put into evidence that the film deposited at RT is highly transparent in the visible region with average transmittance greater than 84%. Higher substrate temperatures result in a slight decrease of transmittance. Moreover, the direct optical band gap decreases while the refractive index increases with increasing the substrate temperature. Thus, the obtained results reveal that ultraviolet-visible can be considered as a potential material for optical and photovoltaic applications.

Abstract: This work focused on the printing of semiconductor TiO₂ thin films for solar cell applications by 3D printing system. We demonstrate a Liquid Deposition Modeling (LDM) type for controlling the pattern of TiO₂ electrode. The advantage of this type of printer is able to vary the numbers of printed layer as well as different levelling pattern of TiO₂ thin films by one time operation. Our aim was to study the effects of operating parameters of the 3D printer, such as nozzle size, speed and pressure on the thickness and uniformity of the printed TiO₂ films. Using a commercial TiO₂ paste, TiO₂ precursor films were deposited on a conductive F-doped SnO₂ glass by adjusting nozzle size, speed and pressure. The precursor films with different printed layers and levelling pattern were sintered using oven to produce porous TiO₂ electrodes. The thickness and surface roughness of obtained TiO₂ electrodes were characterized using Scanning Electron Microscope (SEM) and 3D Measuring Laser Microscope. The printed TiO₂ substrates were applied to dye-sensitized solar cells as electrodes. Our LDM type 3D printing will provide a new way of levelling design of device components for versatile optoelectronic applications.

Abstract: TiO₂ thin films coated on glass substrates for self-cleaning applications were prepared by sol-gel dip-coating technique. The influence of annealing temperature and air exposure time on wettability was investigated by a water contact-angle measurement. Thermal annealing at temperatures of 100, 200 and 300 °C in air were conducted to the films. Surface morphology of the films was observed by FE-SEM. Elemental distribution and optical properties were examined by EDX mapping and UV-Vis transmission spectroscopy, respectively. Atomic bonding was confirmed by FTIR. The contact angle reached a maximum when the films were annealed at 200 °C. The contact angles of the as-synthesized films were 61.4±2.7°. During storage in air for 20 days, the contact angles increased to 143.1±2.1°. The films were further reannealed with 100 °C for 20 min, the contact angles were enhanced to 153.1±1.3°. The association of contact angle among the surface morphology, elemental distribution and atomic bonding of the films will be discussed.

Abstract: Titaniumdioxide (TiO₂) Thin Films Have been Fabricated and Deposited on Ftoglass Substrates by Spray Pyrolysis Deposition (SPD) Method. the TiO₂thin Films were Annealed at Four Different Temperatures for an Hour. Thetemperature was Set at 100°C, 300°C, 400°C and 500°C. Surface Morphology Andelectrical Properties of TiO₂ Thin Films were Investigated Usingfesem and 2 Point- Probe I-V Measurement, Respectively. the FESEM Result Shows Thatthe Grain Size of the Tio₂ increases when Annealed Temperatureincreases. for XRD Test Shows that the Crystallinity Improved with Theincreasing of Annealing Temperature. when the Annealing Temperature Increases,the Electrical Properties of TiO₂ Also Change. the Result Shows Thatthe Optimum Temperature for Annealing of TiO₂ Thin Film was 400°C.

Abstract: TiO₂ thin films with outstanding photocatalysis can potentially be used for photocatalysis device in the field of environmental protection. TiO₂ thin film (99.99%) was fabricated successfully by power metallurgy. The effect of sputtering power on TiO₂ thin films by radio frequency magnetron sputtering was investigated. The results show that the higher sputtering power is beneficial for the growth of Rutile structure with superior photocatalysis. With the increasing of sputtering power, the rate of methyl orange degradation increases under UV light irradiation. The degradation rate of TiO₂ thin film under sputtering power 75W and 165W is 40% and 80% respectively. This is attributed to the increase of the rutile phase with many defects and dislocation network under higher sputtering power.

Abstract: Titanium dioxide (TiO₂) nanothin films were deposited on unheated substrate, the glass slide and Si-wafer, by DC reactive magnetron sputtering with different substrate-target distance (d_st), in range of 8 to 14 cm. The structural, surface morphology and transmittance spectrum of TiO₂ thin films were characterized by grazing-incidence X-ray diffraction (GI-XRD), atomic force microscopy (AFM) and spectrophotometer, respectively. XRD results show that as-deposited TiO₂ films with short substrate-target distance have only anatase crystal structure corresponding to the anatase in (101) and (200) plane, and turn to be amorphous with long substrate-target distance. The thickness and roughness varied from 50 nm to 142 nm and 1.6 nm to 3.5 nm, respectively. The as-deposited TiO₂ films exhibited high visible transmittance. The optical constants of the films, refractive index (n) and extinction coefficient (k), were calculated by Swanepoel method, at 550 nm, was about 2.43 - 2.76 and 0.082 - 0.187, respectively. The energy band gap (E_g) of the as-deposited TiO₂ films in the range of 3.20 - 3.25 was observed.

Abstract: Pure TiO₂, Nd³⁺doped TiO₂ and Nd ³⁺-CTAB co-doped TiO₂ nanometer thin films were prepared by the sol-gel technique with tetrabutyl titanate and neodymium nitrate as raw materials and surfactant cetyltrimethylammonium bromide (CTAB) as template. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Visible absorbance spectroscopy (UV-Vis). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange. The results show that the all samples calcined at 500°C are all anatase, and there are slight red shifts of the Nd³⁺doped TiO₂ and Nd³⁺-CTAB co-doped TiO₂ films compared with pure TiO₂ films and the red shift of Nd ³⁺-CTAB co-doped TiO₂ is more obvious than that of Nd ³⁺ doped TiO₂, which is beneficial to improve the photocatalytic efficiency. The1.0% Nd³⁺-CTAB co-doped TiO₂ nanometer film calcined at 500°C had excellent photocatalytic efficiencies and the degradation rate of the film is more than 90% after 120 min.

Abstract: Titanium dioxide (TiO₂ ) thin films have been deposited on glass substrates under various conditions by using a homemade reactive DC sputtering technique. The TiO2 has unique characteristics and economical alternative material for transparent conductivity oxide thin films compared with other materials. In this study, titanium (Ti) has been used as a target while argon (Ar) and oxygen (O22</subthin films has been measured by using a calibrated I-V meter. On the other hand, the transparency, microstructure and component of TiO2 thin films have been investigated respectively by using UV-VIS spectrophotometer, XRD and SEM (EDX). The thickness of TiO2 films, the grain size and the band gap have been also successfully estimated. As a result, the conductivity of films increased for Dt at 1 hour to 3.5 hours and decreased for Dt at 4 hours. It means that the optimum Dt was at about 3.5 hours. It may be related to the thickness (structures) of the films. In addition, the thickness and grain size increased by increasing Dt, while the band gap decreased when the film structure changed from non-crystalline structure to crystalizing structure.

Abstract: This research, deals with modification of sol gel process for the synthesis of porous TiO₂-PEG thin films with good structural integrity for environmental self-cleaning applications. Relatively, by adding the PEG with various molecular weights (300, 400, and 600) could influence the formation of TiO₂ films structure and adhesion. Moreover, the formation of porous TiO₂ associated with larger pores will accelerate the mass transfer of the treated contaminants in the larger pore channels. The advantages of the unique structures of as-prepared TiO₂₂ films in the application of environmental self-cleaning systems are extensively studied by characterizing the produced films using various advanced characterization tools. Adhesion of TiO₂ thin films become smooth and better surface with increasing the coating layers. The X-ray Diffraction spectrum of prepared coating shows present of anatase phase as major phase.

Abstract: A rapid optical inspection system for rapid measuring the surface roughness of titanium dioxide (TiO2) thin films is developed in this work. The incident angle of 60° is a good candidate for measuring surface roughness of TiO2 thin films and y = 90.391x + 0.5123 is a trend equation for predicting the surface roughness of TiO2 thin films. Roughness average (Ra) of TiO2 thin films (y) can be directly deduced from the peak power density (x) using the optical inspection system developed. The results were verified by white-light interferometer. The best measurement error rate of the optical inspection system developed can be controlled about 8.8%.The saving in inspection time of the surface roughness of TiO2 thin films is up to 83%.