Titanium Dioxide Thin Films Research Articles

Study the Influence of Tin Oxide SnO2 Doping on the Optical and Structural Properties of Titanium Oxide TiO2

Titanium dioxide thin films, along with varying tin oxide ratios, were applied onto quartz substrates through pulsed laser deposition. The samples included pure TiO2 and doped versions ranging from 5% to 25%. The deposition parameters were kept constant at an energy level of 1000 mJ and a frequency of 6 Hz. Analysis via atomic force microscopy revealed that higher doping percentages correlated with increased surface roughness and grain diameter, indicating larger particle growth. Additionally, the absorption coefficient rose with higher doping ratios, peaking at 25% SnO2. This increase in absorption coefficient accompanied a decrease in the optical energy gap due to thicker film deposition, leading to higher absorbance and lower transmittance.

Assessing the Aging Effect on Ti/Au Bilayers for Transition-Edge Sensor (TES) Detectors.

Transition-edge sensor (TES) microcalorimeters are advanced cryogenic detectors that use a superconducting film for particle or photon detection. We are establishing a new production line for TES detectors to serve as cryogenic anticoincidence (i.e., veto) devices. These detectors are made with a superconducting bilayer of titanium (Ti) and gold (Au) thin films deposited via electron beam evaporation in a high vacuum condition on a monocrystalline silicon substrate. In this work, we report on the development of such sensors, aiming to achieve stable sensing performance despite the effects of aging. For this purpose, patterned and non-patterned Ti/Au bilayer samples with varying geometries and thicknesses were fabricated using microfabrication technology. To characterize the detectors, we present and discuss initial results from repeated resistance-temperature (R-T) measurements over time, conducted on different samples, thereby augmenting existing literature data. Additionally, we present a discussion of the sensor's degradation over time due to aging effects and test a potential remedy based on an easy annealing procedure. In our opinion, this work establishes the groundwork for our new TES detector production line.

Strong coupling in an asymmetric two-dimensional guided mode resonance metasurface structure and enhancement for optical third-harmonic generation

A two-dimensional guided mode resonance structure supports a transverse magnetic (TM) resonant mode in the direction of incident polarization and a transverse electric (TE) resonant mode in the direction perpendicular to the polarization. In this work, the coupling between the transverse magnetic and the transverse electric resonant modes in an asymmetric two-dimensional dielectric metasurface structure is investigated. The asymmetric structure consists of a two-dimensional square nanohole array etched in a titanium dioxide thin film on a transparent silica substrate. With finite difference time domain simulations, anti-crossing of the resonant spectra of the TM and TE modes is observed by adjusting the asymmetry of the structure. The anti-crossing indicates that the interaction between TM and TE resonant modes results in a strong coupling state. A coupled harmonic oscillator model is used to explain the strong coupling effect. The results of the coupled harmonic oscillator modeling agree well with the results of numerical simulations. Furthermore, it is shown that the strong coupling can significantly enhance the third harmonic generation intensity compared with the uncoupled TM and TE resonant modes.

Cobalt Ion-Modified Titanium Oxide Nanorods: A Promising Approach for High-Performance Electrochromic Application

The development of novel cathodic materials with tailored nanostructures is crucial for the advancement of electrochromic devices. In this study, we synthesized cobalt-doped titanium dioxide (Ti-Co) thin films using a facile hydrothermal method to investigate the effects of cobalt doping on their structural, morphological, and electrochromic properties. Comprehensive characterization techniques, including X-ray diffraction and Raman analysis, confirmed the highly crystalline nature of the Ti-Co thin films, with specific Raman bands indicating distinct modifications due to cobalt incorporation. The TiO2 nanorods, optimally doped with cobalt (TC-3), demonstrated enhanced charge transport and mobility, significantly improving the electrochromic performance. Among the various compositions studied, the TC-3 sample exhibited superior lithium-ion accommodation, achieving an optical modulation of 73.6% and a high coloration efficiency of 81.50 cm2/C. It also demonstrated excellent electrochromic stability, maintaining performance for up to 5000 s of coloring/bleaching cycles. These results confirm the beneficial impact of cobalt doping on the structural and functional properties of the host material. Furthermore, the practical effectiveness of the TC-3 thin film was validated through the fabrication of an electrochromic device, which showed efficient coloration and bleaching capabilities. This comprehensive research enhances the understanding and functionality of Ti-Co nanorod architectures, highlighting their promising potential for advanced electrochromic applications.

Characterization of the structure, morphology, and optical properties of titanium dioxide thin film deposited by spray pyrolysis technique for self-cleaning glass

Abstract The research in material science has actively pursued the creation of self-cleaning materials, especially for windows. Titanium dioxide (TiO2) is considered a promising substance for developing hydrophilic self-cleaning surfaces due to its photocatalytic activity. In this research, TiO2 nanoparticles were synthesized using TiCl3 as the precursor and co-precipitation as the experimental method in order to obtain anatase phase. The nanoparticles, then, was deposited by spray pyrolysis technique with different spraying time; 1, 2, 3, and 4 minutes and different types of TiO2 nanoparticles—synthesis and commercial—as the primary variations. TiO2 thin film was formed using ethyl cellulose as binder and isopropyl alcohol as solvent. The synthesized TiO2 nanoparticles and deposited thin film were, then, characterized using XRD, Maud software, UV-Visible Spectrophotometer, optical microscope, and SEM. The higher band gap energy value of TiO2 thin films was obtained with the average of 3.746 eV and 3.744 eV for TI(S) and TI(C), respectively, as a result of ethyl cellulose composition on the thin film. The thin film was categorized as hydrophilic.

Enhancement of electrochromic efficiency of TiO2 nanorods

In this study, the rutile TiO2 nanorods thin films were deposited via hydrothermal method on fluorine-doped tin oxide (FTO) substrate. To form a porous morphology layer, a thin film of amorphous titanium oxide (TiOx) was deposited on the TiO2 nanorods through sputtering at high pressure. The samples were annelid at 450ᵒC to transform the amorphous surface to anatase phase. Structural, optical, morphology and electrochemical properties of the samples were examined via X-ray diffraction (XRD), Raman scattering, UV–Vis NIR and photoluminescence (PL) spectroscopies, field-emission scanning electron microscopy (FE-SEM) and Potentiostat device respectively. The samples exhibited a large optical bandgap of 3.35–3.40 eV and high transparency of over 77 % at a wavelength of 555 nm. Raman analysis confirmed the formation of anatase phase on the rutile nanorods under thermal treatment. PL analysis indicated that the oxygen vacancies reached their maximum after sputtering, while the intensity of PL emission significantly increased after annealing. Investigation of the electrochromic properties revealed an increase in coloration efficiency from 2.6 C−1cm2 for bare nanorods to 10.0 C−1cm2 for nanorods after sputtering deposition, which decreased to 5.4 C−1cm2 after thermal treatment.

Structural and optical properties of highly Ag-doped TiO2 thin films prepared by flash thermal evaporation

The present study investigates the structural and optical properties of silver (Ag)-doped titanium dioxide (TiO2) thin films prepared via flash thermal evaporation using TiO2 and Ag powders mixture at various mass ratios. The crystallinity and surface morphology of the films were studied by varying the percentage of Ag content. Structural properties were characterized using X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM), while optical properties were assessed through optical transmission spectra analysis. Results indicate that Ag doping enhances crystallinity, as evidenced by XRD and Raman spectroscopy, and induces surface plasmon resonance (SPR) absorption attributed to Ag nanoparticles. SEM micrographs reveal agglomerated silver particles on the film surface, confirming Ag diffusion during annealing. Surface analysis through Secondary Ion Mass Spectrometry (SIMS) measurements illustrated the diffusion of Ag within the TiO2 samples and its subsequent accumulation at the surface. We have suggested that the crystallization observed in the evaporated TiO2-Ag thin films may primarily result from the thermal diffusion of Ag metal rather than the annealing process alone. Optical transmission spectra demonstrate a shift in the absorption edge towards the visible region with increasing Ag concentration, indicating enhanced light absorption properties.

Optical response and temperature shielding coatings using tri-layer structure composed of titania/silica/titania

The fabrication of metamaterials with inspiration from nature paved the door for the creation of revolutionary passive and active devices. Butterfly wings are one of them, and their multilayered structure motivated nanotechnologists, physicists, and other optoelectronic and photonic engineers to develop photonic crystals, dielectric reflectors, and Bragg reflectors for use in visible light communication, solar cells, and other photonic and optoelectronic applications. We report the sol–gel spin coating of a dielectric reflector on the glass substrate, an optical passive component consisting of titania and silica thin films for infrared radiation reflection. Individual thin films of titania and silica on glass substrates were studied using an x-ray diffractometer, which indicated anatase of titania and the amorphous nature of silica at a Bragg angle of 25° with a sharp and wide peak, respectively. The multilayer structure of titania/silica/titania was further investigated using Fourier transform infrared spectroscopy, which revealed the presence of Ti–O–Ti and Si–O–Si vibrational bonds at wavenumbers 546 and 973 cm−1, respectively, as well as the presence of Ti–O–Si vibrational bond at 1100 cm−1. The thickness of the multilayer titania/silica/titania was measured using a cross-sectional field emission scanning electron microscope (FESEM) and found to be 160/240/160 nm, respectively. Finally, reflection investigation on the multilayer structure using ultraviolet–visible–near-infrared spectroscopy validated the reflection of the infrared spectrum area by around 70% and showed to be beneficial for temperature shielding applications on glass furnishings.

Structural and optical characteristics of Cr-doped TiO2 thin films synthesized by sol-gel method

In this paper, undoped and 7 %, and 20 % chromium doped titanium dioxide thin films were synthesized on silicon and quartz substrates by utilizing the sol-gel spin coating process. The films were then annealed at 450 °C. The synthesis process and the effects of doping on the structural, optical, and vibrational properties were studied. XRD analysis showed that the undoped thin film had an anatase phase with a crystalline size of about 15.4 nm. However, as the concentration of chromium increased, the crystalline size decreased, and we obtained a mixed phase of rutile and anatase for doped films. The FTIR spectra revealed that undoped films had Ti–O bonding at 435 cm−1 and bond with stretching at 619 cm−1 wavenumbers, which decreased to 379 cm−1 and 377 cm−1 wavenumbers for 7 % and 20 % Cr doping, respectively. The optical measurements showed that the films were homogeneous and had high transmission, reaching 95 % in the visible range for the undoped thin film and 80 % for higher doping levels of chromium. These films have a remarkable level of transparency, and because of that they are highly regarded in the field of thin-film solar cells. Their optical properties make them an excellent choice for use as optical windows in these types of solar cells. As the amount of chromium in the film increases, the optical bandgap decreases from 3.23 eV to 2.26 eV. This suggests that chromium has a significant impact on the optical properties of these films, which might be helpful to researchers and professionals working in the fields of solar energy, optoelectronic devices, photocatalytic systems, gas sensors, and solar cell passivation.

Highly-selective optical filter for NADH fluorescence detection in multiphoton microscopy

Colorectal cancer (CRC) is a pressing global health concern, emphasizing the need for early detection tools. In this study an optical filter for precise detection of nicotinamide adenine dinucleotide (NADH) fluorescence via two-photon excitation fluorescence (TPEF) was developed. Fabricated with silicon dioxide and titanium dioxide thin films in a Fabry-Perot structure, the filter achieved a peak transmittance of about 95% at 483 nm, with a 12 nm full-width at half maximum. TPEF measurements using a tailored setup and NADH liquid phantoms underscored the filter's significance in selectively capturing NADH fluorescence while mitigating interference from other fluorophores. This work marks a substantial stride towards integrating multiphoton microscopy into conventional colonoscopy, enabling non-invasive, objective optical biopsy for colorectal tissue analysis. Further refinements of the experimental setup are imperative to advance tissue differentiation and enhance CRC diagnosis.

Effects of thermal treatment on the electrical behavior of titanium dioxide thin-films

AbstractElectrochemical biosensors made of titanium dioxide have generated significant interest due to their high sensitivity and selectivity for the detection of a variety of diseases. This study focuses on the impact of thermal treatment in an oxygen environment on the electrical properties of titanium dioxide thin films deposited on silicon substrates using pulsed laser deposition; the films were subjected to temperatures of $$\varvec{100\,\,^{\circ }C}$$ 100 ∘ C , $$\varvec{400\,\,^{\circ }C}$$ 400 ∘ C , and $$\varvec{600\,\,^{\circ }C}$$ 600 ∘ C . The primary objective was to explore how thermal processing influences the electrical characteristics of the thin films, with the goal of enhancing their capacitance and thereby improving the performance of sensors developed by functionalizing these films; X-ray photoelectron spectroscopy revealed the presence of Ti$$^{4+}$$ 4 + , Ti$$^{3+}$$ 3 + and TiO$$_x$$ x species in the untreated thin film and in the heat-treated films, with an increase in TiO$$_x$$ x species observed after oxygen heat treatment. Atomic force microscopy demonstrated a decrease in the surface homogeneity of the films at elevated treatment temperatures, which corresponded to a reduction in capacitive behavior; this was further corroborated by Nyquist plots derived from electrochemical capacitance spectroscopy (ECS). The study found that the electrochemical capacitance at lower frequencies decreased significantly from $$\varvec{1.02\,\, \mu Fcm^{-2}}$$ 1.02 μ F c m - 2 to $$\varvec{0.25\,\, \mu Fcm^{-2}}$$ 0.25 μ F c m - 2 when the treatment temperature was increased to $$\varvec{600\,\,^{\circ }C}$$ 600 ∘ C

Electrochemical Studies of The Corrosion Resistance of Bismuth Titanate Thin Films Deposited by RF Sputtering

Thin films of bismuth titanate were grown on stainless steel (316L) and titanium alloy (Ti6Al4V) substrates using the magnetron sputtering technique. The surface morphology of these films was observed with a scanning electron micrograph (SEM). The electrochemical studies used to evaluate the corrosion resistance of the substrate-coating set were the potentiodynamic polarization (Tafel) tests and electrochemical impedance spectroscopy (EIS), both done in a solution of NaCl (3%) as an electrolyte. The SEM showed that the morphology of the coatings grown on a titanium alloy Ti6Al4V substrate was generally homogeneous with a smooth surface but with unmelted material in some regions, while the morphology of the thin films grown on stainless steel 316L was mainly granular, with the presence of a few holes or craters. The potentiodynamic polarization curves showed that the corrosion resistance of the coated samples was better than that of the bare substrate because the corrosion current obtained from the coated samples was lower by two orders of magnitude than that exhibited by the uncoated substrates, and in addition, the corrosion potential of the coated samples was greater than that of the bare substrate. The EIS test showed the presence of a passive thin film of titanium oxide on the titanium alloy substrate.

A study on the fabrication procedure for a high-D/Ti-ratio-deuterated-titanium film on the disk-type neutron generator target

This study aims to present thin film deposition and deuterium adsorption procedure to fabricate disk-type targets with high D/Ti values for a neutron generator and increase their lifespan. The neutron target consists of a titanium thin film with hydrogen loading, and a copper substrate for heat removal. We optimized the incident deuterium ion beam energy and thin film thickness using Geant4 simulations. Additionally, we calculated the expected neutron yield under the optimized conditions. The hydrogen adsorption conditions were optimized by comparing the H/Ti results as per hydrogen adsorption temperature and loading time using titanium foils of different thickness values. Hydrogen (or deuterium) adsorption ratio is strongly influenced by the surface condition and the deposition conditions of the thin film. A titanium film was deposited in various conditions of plasma DC power and substrate temperature. The quality of the thin film was evaluated through surface roughness evaluation and thin film sheet resistance for each deposition conditions. Subsequently, the hydrogen adsorption results were compared according to the quality of the thin titanium films, and the thin titanium film deposition conditions with the highest hydrogen adsorption ratio were confirmed. The selected conditions were applied to conduct deuterium adsorption. In conclusion, this study underscores the critical relationship between thin film quality and hydrogen (or deuterium) adsorption ratio, reinforcing the importance of optimizing thin film deposition parameters for the design of neutron generator disk-type targets with high quality of film and extended lifespan.

Characterization of Flower Based Organic Dyes and Titanium Dioxide Thin Film for Dye Sensitized Solar Cell

In the present study, we described the organic dye extraction process from local flowers employing different methods and solvents (a mixture of acetic acid and ethanol, another is only acetic acid); especially we completed our research by exploring dye from red gerbera flower as it showed higher absorbance. Both dry and fresh petals of the flower were used for extracting dyes. The results revealed that the mixture-based dye extraction from dry red gerbera yielded a higher absorbance value of 4.579 a.u., whereas the acetic acid-based extraction from the same source exhibited a lower absorbance value of 2.778 a.u. The choice of solvent for dye extraction was found to significantly influence the absorption spectrum. Additionally, the Beer-Lambert law was employed to analyze the relationship between the absorbance and the concentration of the extracted dyes. For the electrode, a TiO2 film was created using the spin coating technique. From the XRD graph, we found the band gap energy of TiO2 which is 2.81eV (annealed at 450°C), the type of nanoparticle of the thin film. Also found a Crystallite size of 32.95nm and a specific Surface Area (SSA) of 43.048 m2.g−1, Microstrain (ε) of 5e-3 and Dislocation Density (δ) of 9.2e-4cm−2.

Nanocavity-Mediated Purcell Enhancement of Er in TiO2 Thin Films Grown via Atomic Layer Deposition.

The use of trivalent erbium (Er3+), typically embedded as an atomic defect in the solid-state, has widespread adoption as a dopant in telecommunication devices and shows promise as a spin-based quantum memory for quantum communication. In particular, its natural telecom C-band optical transition and spin-photon interface make it an ideal candidate for integration into existing optical fiber networks without the need for quantum frequency conversion. However, successful scaling requires a host material with few intrinsic nuclear spins, compatibility with semiconductor foundry processes, and straightforward integration with silicon photonics. Here, we present Er-doped titanium dioxide (TiO2) thin film growth on silicon substrates using a foundry-scalable atomic layer deposition process with a wide range of doping controls over the Er concentration. Even though the as-grown films are amorphous after oxygen annealing, they exhibit relatively large crystalline grains, and the embedded Er ions exhibit the characteristic optical emission spectrum from anatase TiO2. Critically, this growth and annealing process maintains the low surface roughness required for nanophotonic integration. Finally, we interface Er ensembles with high quality factor Si nanophotonic cavities via evanescent coupling and demonstrate a large Purcell enhancement (≈300) of their optical lifetime. Our findings demonstrate a low-temperature, nondestructive, and substrate-independent process for integrating Er-doped materials with silicon photonics. At high doping densities this platform can enable integrated photonic components such as on-chip amplifiers and lasers, while dilute concentrations can realize single ion quantum memories.

Transmission electron microscopy reveals clusters of Au–Ag nanoparticles formed in TiO2 thin film, with enhanced plasmonic response

This work reports on the influence of nanoparticle (NP) size distribution and the chemical nature of gold (Au) and/or silver (Ag) NPs in the localized surface plasmon resonance (LSPR) responses. The NPs were produced embedded in a titanium dioxide (TiO2) thin film, deposited by reactive magnetron sputtering technique followed by in-vacuum thermal treatment at 400 °C. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) gave quantitative key information in terms of both the size and distribution of the noble metal NPs. The average Feret diameter was 17 nm (σ = 8) and 55 nm (σ = 28) for Au/TiO2 and Ag/TiO2 films, respectively, while the Au–Ag/TiO2 film showed intermediate values, with an average size of 22 nm (σ = 9). HAAD-STEM, complemented by EDX chemical mapping, revealed an unusual formation of cluster structures containing local distributions of bimetallic (alloyed) Au–Ag NPs. The synergetic characteristics and properties of such bimetallic Au–Ag NPs resulted in an outstanding LSPR sensitivity compared to the monometallic counterparts. Furthermore, the analysis of the average nearest neighbor distances (about one order of magnitude lower than counterparts) suggests the existence of plasmonic hotspots relevant to be explored in sensing and surface-enhanced spectroscopies.

THE EFFECT OF THE DC-SPUTTERING PROCESS ON CHANGES IN THE HARDNESS VALUE AND ELEMENTS COMPOSITION OF BIOCOMPATIBLE STAINLESS STEEL 316L MATERIAL

Titanium Dioxide (TiO2) thin films have intriguing optical, photocatalytic, and electrical properties and have been investigated for various applications, including solar cells, biomaterials, corrosion-resistant materials, and gas sensor. In this study, TiO2 thin films were deposited on the surface of 316L Stainless Steel to improve its mechanical properties as an implant material. The deposition method used was DC sputtering with variations in deposition times of 30, 60, 90, 120, and 150 minutes. Vickers hardness test and SEM-EDX characterization were carried out to determine the hardness value, elemental composition, and thickness of the TiO2 thin film formed. Based on these tests, it was discovered that the optimal hardness value of316L stainless Steel material was attained at a deposition period of 90 minutes with a hardness value of 170.10 VHN, and the average thickness of the layer formed was ± 119.02 μm.

Microstructural, optical, and photocatalytic properties of TiO2–Bi2O3–GO thin films obtained by sol-gel for applications with sunlight

The following study presents the structural, optical, and photocatalytic properties of thin films of titanium dioxide (TiO2) and bismuth trioxide (Bi2O3) in their pure state, as well as mixtures of both oxides in different atomic proportions (with respect to Ti and Bi) and as films modified with a dispersed phase of graphene oxide (GO). The films were sintered at 400 °C, 450 °C, 500 °C and 550 °C. The synthesis of the oxides was carried out by the sol-gel method and the material deposits were synthesized by the dip-coating technique. For mixtures with atomic proportions of 50% and 70% Bi2O3, bismuth titanates were obtained with Bi2(Ti2O7) (cubic) stoichiometry at 550 °C and Bi4Ti3O7 (orthorhombic) stoichiometry at 500 °C, respectively. It was determined that the Bi2(Ti2O7) compound presents the best photocatalytic properties in the degradation of tartrazine in aqueous solution using solar radiation, achieving up to 30% in the photodegradation of the dye. The GO was incorporated in 2% p/p to the precursor solutions of TiO2 and Bi2O3; the resulting materials presented a better photocatalytic activity.

Local structural and sensing properties of TiO2 thin film using the PVD method

This paper studied the structural, morphological, optical, and X-ray absorption near-edge spectroscopy (XANES) and sensing properties of titanium dioxide (TiO2) thin film. The TiO2 thin film is prepared in the thin film laboratory on a clean glass plate using a physical vapor deposition (PVD) method. The structural, morphological, Optical, and electronic properties of the fabricated samples are presented by X-ray diffraction (XRD), atomic force microscope (AFM), UV-visible, and XANES. It is found from XRD the crystallite size was ∼25.66 nm with microstrain ∼0.0064 using the Williamson-Hall (W-H) plot. The fractal terms such as grain size, roughness, kurtosis, and skewness were estimated using AFM. The grain size lies in the nanometric range and found that ∼77.21 nm. The band gap of the fabricated film is ∼3.23 eV. The XANES analysis is well supported by XRD measurement and the result found that the fabricated TiO2 thin film was anatase phase. The sensing properties of TiO2 are studied for the detection of Liquified Petroleum Gas (LPG) concentration (0-5000 ppm) at room temperature. Results found that the TiO2 film is highly sensitive and is the fast response for LPG gas sensors with a maximum sensitivity of ∼198 %.

Flexible Antibacterial Respiratory Monitoring Sensor Based on Controllable Au-Modified Surface of Highly {001} Preferred Anatase Titanium Dioxide Thin Film.

Respiratory signals are critical clinical diagnostic criteria for respiratory diseases and health conditions, and respiratory sensors play a crucial role in achieving the desired respiratory monitoring effect. High sensitivity to a single factor can improve the reliability of respiratory monitoring, and maintaining the hygiene of the sensors is also important for daily health monitoring. Herein, we propose a flexible Au-modified anatase titanium dioxide resistive respiratory sensor, which can be mechanically compliantly attached to curved surfaces for respiratory monitoring in different modalities (i.e., respiratory intensity, frequency, and rate). The uniform and preferentially oriented anatase titanium dioxide films gained by the polymer-assisted deposition technique can be fabricated on flexible substrates through a liquid-assisted transferring process. The Au modification can enhance surface plasmon resonance to facilitate the photocatalytic activity of titanium dioxide, and the optimized distribution of Au on the surface of titanium dioxide film made the sensor have an excellent antibacterial effect. The uniquely designed encapsulation can effectively control the contact between the surface of titanium dioxide films and electrodes, allowing the flexible sensor to exhibit fast response time (0.71 s) and recovery time (1.06 s) to respiratory as well as insensitivity or low sensitivity to other factors (i.e., gas composition, humidity, temperature, stress, and strain). This work provided an effective strategy for flexible wearable respiratory sensors and has great potential in daily respiratory monitoring for health management and pandemic control.