Common Glass Substrate Research Articles

Influence of the parameters of fabrication on the optical properties of Bi1.7Ti2O6.624 thin films

We show the results obtained for the growth of Bi1.7Ti2O6.624 thin films through RF magnetron sputtering. The films were grown on common glass substrate, the microstructure was evaluated for all films as a function of the power applied at the target and the substrate temperature, and the optical behavior was evaluated for the most crystalline film. Microstructure analysis was carried out through X-ray diffraction (XRD), and optical response was evaluated by means of transmittance measurements. The XRD results showed that the films grown in a range from room temperature to 573K and at a power from 100W to 200W are amorphous. Moreover, the films grown at 623K and power at 150 and 200W showed preferential orientation along the (311) plane of the Bi1.7Ti2O6.624 cubic-centered face phase. Using the transmittance values and through the Swanepoel method, we calculated the refraction index and the average thickness of the most crystalline film. The refraction index dispersion was studied via the Wemple–DiDomenico relation. The absorption coefficient and the optical band gap were determined through analysis of the free interference region.

Enhanced Photocatalytic Activities of Multi-Modified TiO2 Films on Common Glass Substrates

Boric acid-treated and sulfur ion-doped multi-modified TiO2 films with high photocatalytic activities were prepared on soda–lime glass (Na2O · CaO · 6SiO2) substrates via the sol–gel method. The as-prepared specimens were characterized using high-resolution field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectra, UV–vis diffuse reflectance spectroscopy, and Brunauer–Emmett–Teller surface area. The photocatalytic activities of the films were evaluated by degradation of organic dyes in aqueous solutions. Compared with boric acid treatment and sulfur surface doping, the integration of both methods gave the best results. It is believed that high photocatalytic activity is correlated with the microstructure of the TiO2 film.

Enhanced growth of crystalline-amorphous core-shell silicon nanowires by catalytic thermal CVD using in situ generated tin catalyst

In this work, we prepared silicon nanowires (Si NWs) on both fluorine-doped SnO2 (FTO) coated glass substrate and common glass substrate by catalytic thermal chemical vapor deposition (CVD) using indium film as the catalyst. It is confirmed that indium can catalyze the growth of Si NWs. More importantly, we found that tin generated in situ from the reduction of SnO2 by indium can act as catalyst, which greatly enhances the growth of Si NWs on FTO substrate. The obtained Si NWs have a uniform crystalline-amorphous core-shell structure that is formed via vapor-liquid-solid and vapor-solid growth of silicon sequentially. This work provides a strategy to prepare Si NWs in high yield by catalytic thermal CVD using the low melting point metal catalysts.

Thin-Film Thermal-Conductivity Measurement on Semi-Conducting Polymer Material Using the 3ω Technique

Organic solar cells have gained increasing interest in recent years due to their promising low-cost processing possibility and high throughput compared to inorganic solar cells. Since the efficiency of organic solar cells is still low, further optimization has to be done. Reliable simulation of solar cell layout and performance strongly depends on correct input data of the electrical and thermal transport properties of the applied film materials. In many cases these material properties are only available for bulk material if available at all. Owing to the given film thicknesses on the order of tenths to hundreds of nanometer and to the preparation methods, the properties of the used system can differ from the bulk material values. For determination of the thin-film thermal conductivity, only a few measurement methods are known to provide accurate results with one of them being the 3ω technique. It allows the determination of the thermal conductivity of bulk materials as well as thin films down to a thickness of around 50 nm. This study is part of an investigation on the influence of local hot spots, generated by defects in the active layer of organic solar cells, and on the charge carrier mobility as well as the propagation of the hot spot due to the thermal conduction of the material. Applying the 3ω technique, the effective thermal conductivity of solution-derived poly(3-hexylthiophene) thin films of different thickness on a common glass substrate was investigated.

Influence of Fabrication Parameters on Crystallization, Microstructure, Surface Composition, and Optical Behavior of MgO Thin Films Deposited by rf Magnetron Sputtering

In this work MgO thin films have been grown onto common glass substrates by magnetron rf sputtering from a MgO (99.99%) target with dimensions of 4″×¼″. Basically, we found the optimum conditions for deposition such as working pressure (7×10−3 mbar), the power applied to the target (400 W) and the flow of Ar (20 sccm). The films have been characterized by X-ray diffraction (XRD) at a grazing angle at θ–2θ configuration, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and transmittance studies. The XRD results show that to reproduce the polycrystalline phase of the target, there is a power threshold of 250 W. AFM results indicate that the films present average roughness of the 200 A and grain size of 1100 A. XPS shows a surface composition of the films most external 5 nm, indicating the presence of MgO and Mg(OH)2. The optical characterization indicates that the films have a high absorption coefficient for wavelengths below 310 nm, and between 450 to 850 nm they showed a transmittance average of 90%.

Investigation of ZnO nanorods synthesized by a solvothermal method, using Al-doped ZnO seed films

ZnO nanorods were successfully grown on common glass substrates using a simple solvothermal method via the precursors of zinc acetate dihydrate (Zn(CH 3COO) 2·2H 2O) and Hexamethylenetetramine (C 6H 12N 4) with equal molar concentration at 0.01 mol/l, 0.025 mol/l, 0.05 mol/l, and 0.075 mol/l. The ZnO nanorods were characterized by X-ray diffraction (XRD), Scanning electron microscopy, UV–Vis absorption spectrophotometer and photoluminescence (PL) spectrometer. XRD results indicated that all the ZnO nanorods were preferentially grown along [0 0 0 1] direction ( c-axis). With an increase of Zn(CH 3COO) 2·2H 2O and C 6H 12N 4 concentration, the diffraction intensity of ZnO nanorod along c-axis also increased. Scanning electron microscopy images showed that the well-faceted hexagonal ZnO nanorods were grown vertically from the common glass substrates. In addition, with the increase of Zn(CH 3COO) 2·2H 2O and C 6H 12N 4 concentration, the exciton band of ZnO nanorods determined by UV–Vis absorption spectra gradually became narrow and the intensity of exciton band also remarkably augmented. Photoluminescence spectra showed that with the increase of Zn(CH 3COO) 2·2H 2O and C 6H 12N 4 concentration, the position of emission peak of ZnO nanorod blue-shifts towards shorter wavelength in UV region and the luminescence intensity remarkably enhances in visible emission range (470–630 nm).

Study on ZnS thin films prepared by chemical bath deposition

We reported the deposition and structural characterization of zinc sulfide (ZnS) thin films by chemical bath deposition (CBD) from a bath containing thiourea, ZnSO 4 and ammonia in aqueous solution on common glass substrates. The solution concentration and annealing condition played a very important role on transmissivity, homogeneity, crystal and transmissivity of ZnS thin films. Spectrophotometer, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), digital four-point probe resistance measurement were used to characterize their properties and composition. As a result, transmissivity for the samples were more than 80%. Then it would be stable above 600 nm. The surface morphology of the thin films were homogeneous. However, there were some white spots in the SEM patterns that might be colloidal particles sedimentation mixed with ZnS. These particles could be amorphous or no crystal. According to the detection, ZnS films' resistance were changed with the ZnSO 4 solutions' concentration.

Fabrication and its characteristics of low-temperature polycrystalline silicon thin films

In order to reduce the cost of solar cells or flat-panel display, it is very important to synthesis polycrystalline silicon films on low cost substrate such as glass at low temperature. In this work, electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (PECVD) system was successfully applied to synthesize poly-Si thin-film on common glass substrate using H2 as the plasma source and SiH4 (Ar:SiH4=19:1) as the precursor gas at low temperature. Since the multicusp cavity-coupling ECR plasma source was adopted to provide active precursors, the growth temperature decreased to lower than 200°C. In the plasma, the electron temperatures kTe are ∼2–3 eV and the ion temperatures kTi≤1 eV. This leads to non-remarkable ion impacts during the film deposition. The characteristic of poly-Si films was investigated. It was shown that the crystalline fraction Xc of the films can be up to 90% even deposit at room temperature, and the film was (220) preferably oriented. The growth behaviors of the film between the interface of glass and Si films were also discussed in detail.

Two-step growth of superhydrophobic ZnO nanorod array films

Well-aligned ZnO nanorod array films (ZnO-NAFs) were coatedon common glass substrate by two-step method. A thin buffer layer of ZnO seeds were first deposited via RF magnetron sputtering,the ZnO-NAFS were then grown in a simple aqueous solution. We report a surface-modification induced hydrophilicity to superhydrophobicity transiton on ZnO-NAFs. The sample was characterized by scanning electron microscopy (SEM). The surfaces of ZnO-NAFs was superhydrophobic with a three-phase contact angle of 151°±0.5°, while the sliding angle is 7°. The superhydrophobicity of ZnO-NAFs was validated by Cassie's model.

Plasma annealing: A route to precise controlled growth of MoO 3 nanostructures

This paper discusses a novel technique for growth of molybdenum oxide nanostructures on common glass substrates with precise control over their number density, shape and dimension. The method involves thermal evaporation of MoO 3 powder on two types of substrates; glass and nickel (Ni)-coated glass substrates, at room temperature. MoO 3 deposited on each type of substrate was annealed in two different ambients; in air and oxygen plasma. Our experimental results revealed that by changing annealing duration only and keeping all other experimental conditions constant, nanostructures with well-defined size and shape were obtained only on Ni-coated glass substrates by annealing in air or oxygen. These experiments divulged that Ni-provided heterogeneous nucleation sites for formation of nuclei that further grew into nanostructures. The shape of nucleus during growth was determined by a combination of three factors; interfacial energies, elastic strain energies and minimization of surface energies, each active at different stages of growth.

Crystallographic structure and surface composition of [formula omitted] thin films grown by RF magnetron sputtering

In this work we report on the results obtained on NbNx thin films grown on both common glass and silicon wafer substrates by RF magnetron sputtering at different substrate temperatures and different target power supplies. The crystalinity, morphology and surface composition of the deposited films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively.

Electrical transport properties of MoO3 thin films prepared by laser assisted evaporation

AbstractIn the present paper the growth of MoO3 thin films on common glass substrates are described. The films were prepared by evaporation of a MoO3 target with a CO2 laser (10.6 μm), operating in the continuous wave mode. The effect of substrate temperature on the crystallographic structure and electrical properties of MoO3 thin films was studied. The chemical composition of the different species formed on the films surface was obtained by X‐ray photoelectron spectroscopy (XPS) and the crystalline structure was studied with X‐ray diffraction (XRD). The electrical conductivity of the films was determined using the standard four‐points method. Conductivity of the films varied from de 10–9 to 10–5 (Ωcm)–1 in the 300‐600 K temperature range. Arrhenius‐type plots for the electrical conductivity indicate the presence of at least two different conduction mechanisms. The I‐V characteristic curve shows an ohmic behavior only in the 4.5‐60 V range. Outside this interval the I‐V curve has a behavior described by a power law. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of substrates on the properties of p-type ZnO films

Influence of substrates on the properties of p-type ZnO films, which were fabricated by N–Al co-doping technique, was studied. Hall measurement results indicated that ZnO films deposited on common glass substrate were p-type conductivity when Zn:N:Al atomic ratio amounts to 1:3:0.1. However, ZnO films deposited on corning 7059 glass substrate showed n-type conductivity. Secondary ion mass spectroscopy demonstrated that Na content incorporated into ZnO films deposited on common glass substrate was more evident than that of corning 7059 glass. In addition, Hall mobility and conductivity of p-type ZnO thin films deposited on silicon substrate were improved largely.

Preparation and Characterization of Titania Thin Films

TiO2 sol with steady suspension and high photocatalytic activity was prepared via a precipitation-peptization method. The XRD results indicate that the TiO2 sol exhibited an anatase structure. TiO2 films on woven fabrics (carbon, PET and Nylon), prepared via dip-coating with TiO2 sol, were characterized by XRD and SEM analysis. The dependence of the woven fabrics properties on the amount of TiO2 coated and photocatalytic activity were also studied. When the diameter of fibers is smalle, large quantity of TiO2 is coated on woven fabrics leading to an improvement in the photocatalytic activity. It is observed that the photocatalytic activity of TiO2 film coated on woven fabrics exceeds that of TiO2 film coated on common glass substrate with the same surface area.

Enhanced Coupling of Light from Organic Electroluminescent Device Using Diffusive Particle Dispersed High Refractive Index Resin Substrate

To improve light extraction from organic electroluminescent (EL) devices, we introduced a diffusive substrate with 25 μm thickness consisting of high refractive index resin and scattering particles. It is expected that the diffusive substrate with high refractive index matrix converts the waveguided emission into external emission from both glass substrate and indium-tin-oxide/organic layer. We used the ray tracing method to optimize the scattering effect and to verify the coupling out effect of the diffusive high refractive index substrate. With the use of the ray tracing calculation, an increase in the external emission up to a factor of 2.7 was expected compared to use of a common glass substrate. Experimentally, the coupling out effect of the diffusive high refractive index substrate strongly depended on the thickness of electron transporting layer (ETL) due to the well-known interference effect. The current efficiency increased by a factor of 1.3 for an organic EL device with a 60-nm-thick ETL and by a factor of 6.8 for one with a 120-nm-thick ETL.

Tin-Diffused Glass Slab Waveguides Locally Covered with Tapered Thin TiO2 Films for Application as a Polarimetric Interference Sensor with an Improved Performance

Common soda lime slide glass substrates made by floating molten glass on the surface of molten tin contain a tin-diffused layer that is demonstrated to be a low-loss polarization-insensitive slab optical waveguide. In this study, such a tin-diffused waveguide was locally covered with a tapered thin TiO2 film to form a composite structure in which the zeroth-order transverse electric (TE0) and magnetic (TM0) modes are spatially separated from each other. This feature enables the composite structure to serve as a highly sensitive polarimetric interferometer. Moreover, a negligible modal birefringence of tin-diffused waveguides offers the polarimetric interferometer an improved performance relative to those fabricated earlier using single-mode potassium ion-exchanged glass waveguides. In situ detection of both the protein adsorption and a small change in refractive index of liquid was accomplished using the tin-diffused waveguide-based polarimetric interferometer. With horse heart myoglobin, adsorption from aqueous solution less than 0.125 monolayer coverage can cause the interferometer to yield a phase-difference change of delta phi = 2pi.

Optical behaviour of pH detectors based on sol–gel technology

Acidity is an outstanding parameter that affect the correct preservation of most part of materials engaged in artworks and heritage objects. In spite of the new generation of advanced analytical devices, the conservation/heritage management sector claims for some kind of simple, robust and low-cost device to monitor environmental acidity wherever necessary. The purpose of this paper is to offer a suitable alternative for the estimation of environmental acidity by means of detectors to be used without electrodes, solutions, pH meters, wires or batteries. Doped sol–gel thin coatings have been used as transductors for producing pH detectors. The coatings consist of a partially densified polysiloxane network and an organic dye sensitive to pH changes. The siloxane network behaves as a host for immobilisation of the dye molecules, in such a way that chemical–optical properties of the dye are preserved as far as possible. The transductors were applied on common glass substrates by dipping. Further heat-treatment allows the coating partial densification. The optical response of the detectors was analysed by VIS absorption spectroscopy, since a change of colour took place when the detectors were submitted to different pH buffered solutions. With the aim to investigate their optical behaviour as a function of pH, several experimental measurements were undertaken: absorption intensity; maximum spectral wavelength; colour coordinates; colour purity percentages. Time response and memory effect were also studied. The detector operation conditions for monitoring environmental acidity both indoor and outdoor are discussed.

Control of Nucleation in Solution Growth of Anatase TiO2 on Glass Substrate

Low-temperature preparation of ceramic thin films in aqueous solution is an important new field in the synthesis of functional materials. This work examines control of nucleation in the growth of anatase titania (TiO2) on a common glass substrate at 55−80 °C using an inorganic precursor, TiF4. It is found that TiO2 on fused silica is first formed as single-crystalline nuclei during an initial heterogeneous nucleation. These TiO2 crystallites elongate along the [001] direction with their [110] axis perpendicular to the glass substrate; the elongated nuclei later grew into a round flowerlike morphology owing to a significant increase in homogeneous nucleation rate during the continued growth. The flowerlike polycrystalline TiO2 islands, either as discrete crystallites or as lined crystallite arrays, subsequently develop into a planar crystallite monolayer. In general, low-pH condition suppresses heterogeneous nucleation and growth; this allows a self-alignment of thin threadlike crystallites. In contrast, h...

BiVO 4 thin film preparation by metalorganic decomposition

This paper describes the first obtention of BiVO 4 thin films. These films were prepared with the Metalorganic Decomposition technique, starting from bismuth 2-ethyl-hexanoate and vanadium (IV) (oxy)acetylacetonate precursors. These compounds were dissolved in freshly distilled acetylacetone, dip-coated on common borosilicate glass substrates and pyrolysed at 400°C. Film thickness ranged from 50 to 100 nm, depending on the number of deposition steps. Films are transparent, allowing the first obtention of UV–vis absorption spectra acquisition in transmission mode. Raman microprobe spectra confirmed the obtention of BiVO 4 deposited as an homogeneous film. Scanning electron micrographs showed a continuous and porous surface.

Optimization of Homogeneous Refracting Waveguide Lens Systems by Ray Tracing

Abstract A method for the optimization of homogeneous reflecting waveguide lens systems by means of ray tracing is described. An approach for the automatic correct synthesis of the trial lens systems and a merit function, which provides very stable convergence of the optimization procedure, are used. The diffraction properties of the optimized lens systems, which can be prepared by double K+−Na+ and Ag+−Na+ ion-exchange in a common glass substrate, are studied numerically. The five-lens system optimized to focus a parallel beam has a very good off-axis performance over field angles up to 18°.