Fabrication and characterization of superhydrophobic thin films based on TEOS/RF hybrid

Preparation of superhydrophobic silica-based thin film by adjusting different concentration of reverse (W/O) emulsion of resorcinol formaldehyde resin (re-RF) which was hybridised with silica sol has been developed. The hybrid films were coated by the mixing solution which included precursor solution (sol-gel process) and re-RF (sol-gel process). Rough surfaces were obtained by removing the organic polymer at high temperature and then the hydrophobic groups bonded onto the films were obtained by the reaction with trimethylchlorosilane (TMCS). Characteristic properties of the as-prepared cross-section and surface of the films were analyzed by scanning electron microscopy (SEM) and atom force microscopy (AFM). The experimental parameters are mainly varied the weight ratio of re-RF to silica sol from 0.2 to 4.0. The result showed that the contact angle of the modified silica film was greater than 160° when the weight ratio of re-RF to silica sol was 2.0.     

Fabrication of stable, transparent and superhydrophobic nanocomposite films with polystyrene functionalized carbon nanotubes

Stable, transparent and superhydrophobic carbon nanotube (CNT) nanocomposite films were fabricated by one-step spray casting process using the polystyrene functionalized CNTs, which were prepared by “living” free-radical polymerization and analyzed by means of infrared spectroscopy and thermal gravimetric analysis. The CNT film has a high water contact angle of 160° and a sliding angle of less than 3°. The surface topography of the fabricated film was characterized by field emission scanning electron microscopy. The transparency of the CNT film was investigated by UV–vis spectroscopy. The result shows that the CNT film has light transmittance of about 78% in the visible light region.     

Optically transparent, superhydrophobic methyltrimethoxysilane based silica coatings without silylating reagent

The superhydrophobic surfaces have drawn lot of interest, in both academic and industries because of optically transparent, adherent and self-cleaning behavior. Surface chemical composition and morphology plays an important role in determining the superhydrophobic nature of coating surface. Such concert of non-wettability can be achieved, using surface modifying reagents or co-precursor method in sol-gel process. Attempts have been made to increase the hydrophobicity and optical transparency of methyltrimethoxysilane (MTMS) based silica coatings using polymethylmethacrylate (PMMA) instead of formal routes like surface modification using silylating reagents. The optically transparent, superhydrophobic uniform coatings were obtained by simple dip coating method. The molar ratio of MTMS:MeOH:H₂O was kept constant at 1:5.63:1.58, respectively with 0.5 M NH₄F as a catalyst and the weight percent of PMMA varied from 1 to 8. The hydrophobicity of silica coatings was analyzed by FTIR and contact angle measurements. These substrates exhibited 91% optical transmittance as compared to glass and water drop contact angle as high as 171 ± 1°. The effect of humidity on hydrophobic nature of coating has been studied by exposing these films at relative humidity of 90% at constant temperature of 30 °C for a period of 45 days. The micro-structural studies carried out by transmission electron microscopy (TEM).     

Fabrication of superhydrophobic surface of hierarchical ZnO thin films by using stearic acid

Flower-like hierarchical ZnO microspheres were successfully synthesized by a simple, template-free, and low-temperature aqueous solution route. The morphology and microstructure of the ZnO microspheres were examined by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The bionic films with hydrophobicity were fabricated by the hierarchical ZnO microspheres modified by stearic acid. It was found that the hydrophobicity of the thin films was very sensitive to the added amount of stearic acid. The thin films modified with 8% stearic acid took on strong superhydrophobicity with a water contact angle (CA) almost to be 178° and weak adhersion. The remarkable superhydrophobicity could be attributed to the synergistic effect of micro/nano hierarchical structure of ZnO and low surface energy of stearic acid.     

Convenient preparation of ITO nanoparticles inks for transparent conductive thin films

We synthesized Pt and Ag nanowires using a mesoporous silica, SBA-15, as templates. The obtained nanowires are a few micrometers (~4???m) long and 7?nm in diameter. The nanowires are free from bundling and, thus, can be separated as single nanowires. The successful synthesis of such nanowires requires a few considerations. In general, SBA-15 has microchannels on the walls through which the mesopores are interconnected when synthesized at 100?°C or higher. We, therefore, synthesized SBA-15 at a low temperature (80?°C) to eliminate the microchannels. Impregnation of the metal precursors and reduction of them into metals forms metal particles outside the pores in addition to the desired metal nanowires inside the pores. Surface alkylation of SBA-15 prohibits the nucleation of metal on the external surface and exclusively forms the nanowires. Finally, the introduction of surface passivating agent, an alkylthiol, during the removal of the template keeps the nanowires from interacting with one another. The Pt and Ag nanowires so-synthesized were characterized by electron microscopy.     

Preparation of transparent BN films with superhydrophobic surface

A novel approach was investigated to obtain the superhydrophobicity on surfaces of boron nitride films. In this method boron nitride films were deposited firstly on Si(1 0 0) and quartz substrate using a radio frequency (RF) magnetron sputtering system, and then using CF₄ plasma treatment, the topmost surface area can be modified systematically. The results have shown that the water contact angle on such surfaces can be tuned from 67° to 159°. The films were observed to be uniform. The surfaces of films consist of micro-features, which were confirmed by Atomic Force Micrograph. The chemical bond states of the films were determined by Fourier Transform Infrared (FTIR) Spectroscopy, which indicate the dominance of B-N binding. According to the X-ray Photoelectron Spectroscopy analysis, the surface of film is mainly in BN phase. The micro-feature induced surface roughness is responsible for the observed superhydrophobic nature. The water contact angles measured on these surfaces can be modeled by the Cassie's formulation.     

Spin-deposited nanocrystalline lithium ferrite thin films: Fabrication and characterization

Thin films of lithium ferrite (with general composition Li_0.5Fe_2.5O₄) were fabricated at low temperatures (up to 650 °C) by citrate-route using spin-deposition technique. Deposited films consisted of nanometer-sized grains as evidenced by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. XRD patterns for annealed films showed broad peaks exhibiting a spinel phase. Size of nanocrystallites is estimated to be 3-7 nm using Scherrer's equation. Average grain size ∼8.5 nm is observed from TEM images of films annealed at 650 °C. Scanning electron micrographs show the formation of spherical aggregates of around 130 nm in diameter. The AFM analysis clearly evidenced the development of nanograins even at low (∼500 °C) annealing temperatures. Significant decrease in complex dielectric permittivity (∈′ − j∈″) with frequency is observed in the low frequency (100 Hz-1 MHz) as well as in X-band microwave frequency (8-12 GHz) region. ∈′ is found to be in the range of 15.7-33.9 in low frequency region, whereas in X-band microwave frequency region, it is found to lie between 3.9 and 4.9. Similarly, ∈″ is found to be 0.16-5.9 in the low frequency region, and 0.002-0.024 in the X-band microwave frequency region. Room temperature dc resistivity of these films is estimated to lie in the range of 10⁶-10⁸ Ω cm. These results strongly suggest that citrate-route processed nanocrystalline lithium ferrite thin films are promising candidates for monolithic microwave integrated circuits (MMICs).     

Room temperature transparent conducting oxides based on zinc oxide thin films

Doped zinc oxide thin films are grown on glass substrate at room temperature under oxygen atmosphere, using pulsed laser deposition (PLD). O₂ pressure below 1 Pa leads to conductive films. A careful characterization of the film stoichiometry and microstructure using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) concludes on a decrease in crystallinity with Al and Ga additions (≤3%). The progressive loss of the (0 0 2) orientation is associated with a variation of the c parameter value as a function of the film thickness and substrate nature. ZnO:Al and ZnO:Ga thin films show a high optical transmittance (>80%) with an increase in band gap from 3.27 eV (pure ZnO) to 3.88 eV and 3.61 eV for Al and Ga doping, respectively. Optical carrier concentration, optical mobility and optical resistivity are deduced from simulation of the optical data.     

In2O3 透明薄膜晶体管的制备及其电学性能的研究

采用磁控溅射方法在玻璃衬底上生长了In₂O₃晶体薄膜.该薄膜具有(111)晶面择优取向,晶粒尺寸达到33 nm.利用光刻工艺制作了以In₂O₃晶体薄膜为沟道层的底栅式薄膜晶体管.In₂O₃薄膜晶体管具有良好的栅压调制特性,场效应迁移率达到6.3 cm²/(V·s),开关电流比为3×10³,阈值电压为-0.9 V.结果表明,In相似文献   

Fabrication of superhydrophobic cotton fabrics by silica hydrosol and hydrophobization

Superhydrophobic cotton fabrics were prepared by the incorporation of silica nanoparticles and subsequent hydrophobization with hexadecyltrimethoxysilane (HDTMS). The silica nanoparticles were synthesized via sol-gel reaction with methyl trimethoxy silane (MTMS) as the precursor in the presence of the base catalyst and surfactant in aqueous solution. As for the resulting products, characterization by particle size analyzer, scanning electron microscopy (SEM), scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA) were performed respectively. The size of SiO₂ nanoparticles can be controlled by adjusting the catalyst and surfactant concentrations. The wettability of cotton textiles was evaluated by the water contact angle (WCA) and water shedding angle (WSA) measurements. The results showed that the treated cotton sample displayed remarkable water repellency with a WCA of 151.9° for a 5 μL water droplet and a WSA of 13° for a 15 μL water droplet.     

A wet chemical preparation of transparent conducting thin films of Al-doped ZnO nanoparticles

A wet chemical deposition method for preparing transparent conductive thin films on the base of Al-doped ZnO (AZO) nanoparticles has been demonstrated. AZO nanoparticles with a size of 7 nm have been synthesised by a simple precipitation method in refluxed conditions in ethanol using zinc acetate and Al-isopropylate. The presence of Al in ZnO was revealed by the EDX elemental analysis (1.8 at.%) and UV–Vis spectroscopy (a blue shift due to Burstein–Moss effect). The obtained colloid solution with the AZO nanoparticles was used for preparing by spin-coating thin films on glass substrates. The film demonstrated excellent homogeneity and transparency (T > 90%) in the visible spectrum after heating at 400 °C. Its resistivity turned to be excessively high (ρ = 2.6 Ω cm) that we ascribe to a poor charge percolation due to a high film porosity revealed by SEM observations. To improve the percolation via reducing the porosity, a sol–gel solution was deposited “layer-by-layer” in alternation with layers derived from the AZO colloid followed by heating. As it was shown by optical spectroscopy measurements, the density of thus prepared film was increased more than twice leading to a significant decrease in resistivity to 1.3 × 10⁻² Ω cm.     

Deposition and characterization of transparent and conductive sprayed ZnO:B thin films

Highly transparent and conductive Boron doped zinc oxide (ZnO:B) thin films were deposited using chemical spray pyrolysis (CSP) technique on glass substrate. The effect of variation of boron doping concentration in reducing solution on film properties was investigated. Low angle X-ray analysis showed that the films were polycrystalline fitting well with a hexagonal wurtzite structure and have preferred orientation in [002] direction. The films with resistivity 2.54×10⁻³ Ω-cm and optical transmittance >90% were obtained at optimized boron doping concentration. The optical band gap of ZnO:B films was found ∼3.27 eV from the optical transmittance spectra for the as-deposited films. Due to their excellent optical and electrical properties, ZnO:B films are promising contender for their potential use as transparent window layer and electrodes in solar cells.     

Preparation and characterization of transparent NiO thin films deposited by spray pyrolysis technique

Nickel oxide thin films were successfully fabricated with various deposition time (t_d = 5, 10, and 15 min) on glass substrates using spray pyrolysis technique. The deposited films undergo thermal treatment at 350 °C for various annealing time (t_a = 0, 15, 30 and 60 min). In this study, the effect of t_d and t_a on film thickness was observed and their influence on structural, morphological and optical properties were investigated. The films deposited with t_d = 5 min showed amorphous structure while the films grown at higher deposition time became partially crystallized with preferred growth along (1 1 1) direction. Heat treatment carried out in air allowed us to tune the polycrystalline structure and the diffraction intensity at preferred peak increases with the increase in t_a which is a consequence of better crystallinity. This was reflected in the AFM micrographs of the films which suggested that the thermal annealing (or increasing t_a) facilitates the process of grain-growth, and improves the crystalline microstructure. The optical transmission of the films was found to vary with t_d and t_a and thus film thickness. The thinner films show higher transparency in the UV–vis spectral region. The optical band gap was blue-shifted from 3.35 eV to 3.51 eV depending on t_a. The effect of t_a on the various optical constants of the NiO films has also been discussed.     

Fabrication and characterization of fluorine-doped thin oxide thin films and nanorod arrays via spray pyrolysis

This paper reports the synthesis and characterization of fluorine-doped tin oxide (FTO) thin films via intermittent spray pyrolysis utilizing a solution mixture of tin chloride pentahydrate and ammonia fluoride. Utilizing the same solution, nanorod arrays were fabricated via template-based growth. Uniform and crack-free FTO films over 20×20 mm with a thickness up to 900 nm have been routinely achieved; such FTO films demonstrate electrical resistivity as low as 2.2×10^-4 Ω cm as well as good optical transparency ranging from 75 to 85%. In addition, FTO nanorods were fabricated using template-filling methods at a temperature of 440 °C. The nanorods have a diameter of ∼160–250 nm, appear to be comprised of small nanoparticles 5–10 nm in size, and have a resistivity value of 4×10^-1 Ω cm. PACS 81.07.-b; 73.61.-r; 81.16.Be     

Optical property of nanocomposite of mesoporous silica thin films incorporated with gold nanoparticles

Amino-functionalized mesoporous silica thin films (MTFs) are produced using surface active agent F127,and then gold nanoparticles are introduced into the pore channels to prepare the Au/SiO 2 nanocomposite.After assembling the gold,the amino-functionalized MTF undergoes some shrinkage but remains a periodic structure as demonstrated by X-ray diffraction (XRD) patterns.The nanocomposite shows an acute characteristic diffraction peak assigned to (111) plane of the face-centered-cubic structure of gold,indicating that gold nanoparticles crystallize well and grow in a preferred orientation in the pore channels.The surface plasma resonance (SPR) absorption peak near 570 nm undergoes a red-shift accompanied by a strengthening of intensity when HAuCl 4 is used to react with the amino groups on the internal pore surfaces for 4,6,and 8 h.The simulative results are consistent with the experimental ones shows that the absorption property of the Au/SiO 2 nanocomposite is influenced by the dipping time,which affects the size and volume fraction of embedded gold nanoparticles.     

Fabrication of superhydrophobic polyaniline films with rapidly switchable wettability

A superhydrophobic polyaniline (PANI) film has been fabricated by using a facile one-step spraying method. The PANI was synthesized via in situ doping polymerization in the presence of perfluorooctanoic acid (PFOA) as the dopant. The water contact angle of this superhydrophobic surface reaches to 156°. Both the surface chemical compositions and morphological structures were analyzed. A granular morphology of PANI with a moderate amount of nanofibers was obtained. Moreover, a rapid surface wettability transition between superhydrophobicity and superhydrophilicity can be observed when it is doped with PFOA and de-doped with base. The mechanism for this tunable wettability has been discussed in detail.     

Fabrication and characterization of magnetron sputtered arsenic doped p-type ZnO epitaxial thin films

Arsenic doped p-type ZnO thin films were grown on sapphire substrate by magnetron sputtering. As grown films reveal p-type conduction confirmed by Hall-effect and photoluminescence measurements. The p-type film with a hole concentration of 2.16× 10¹⁷ cm⁻³, mobility of 1.30 cm²/V.s and resistivity of 22.29 Ω-m were obtained at substrate temperature of 700 °C. ZnO homojunction synthesized by in-situ deposition of As doped p-ZnO layer on Al doped n-ZnO layer showed p-n diode like characteristics. X-ray pole figure and Transmission Electron Microscope studies confirm epitaxial nature of the films. Photoluminescence results exhibit the peaks associated with donor acceptor pair emission.     

Fabrication and characterization of Pt intermediate transparent and conducting ITO/Pt/ITO multilayer films

Platinum intermediate transparent and conducting ITO/metal/ITO (IMI) multilayered films were deposited by RF and DC magnetron sputtering on polycarbonate substrates without intentional substrate heating. Changes in the microstructure and optoelectrical properties of the films were investigated with respect to the thickness of the intermediate Pt layer in the IMI films. The thickness of Pt film was varied from 5 to 20 nm.In XRD measurements, neither ITO single-layer films nor IMI multilayer films showed any characteristic diffraction peaks for In₂O₃ or SnO₂. Only a weak diffraction peak for Pt (1 1 1) was obtained in the XRD spectra. Thus, it can be concluded that the Pt-intermediated films in the IMI films did not affect the crystallinity of the ITO films. However, equivalent resistivity was dependent on the presence and thickness of the Pt-intermediated layer. It decreased as low as 3.3×10⁻⁴ Ω cm for ITO 50 nm/Pt 20 nm/ITO 30 nm films. Optical transmittance was also strongly influenced by the Pt-intermediated layer. As Pt thickness in the IMI films increased, optical transmittance decreased to as low as 30% for ITO 50 nm/Pt 20 nm/ITO 30 nm films.     

Fabrication and characterization of Ag intermediate transparent and conducting TiON/Ag/TiON multilayer films

Silver (Ag) intermediate transparent and conducting TiON/Ag/TiON (TAgT) films were deposited by RF and DC magnetron sputtering on glass substrates. Changes in the optoelectrical properties of the films were investigated as a function of Ag thickness. The thickness of the Ag film varied from 5 to 20 nm.In XRD patterns, the TAgT films showed characteristic diffraction peaks for Ag (111), (200), (220), and (311) planes, while peaks for TiON were not observed. Thus, it was concluded that the Ag interlayer did not affect the crystalline structures of the upper TiON films. However, electrical resistivity was dependent on the thickness of the Ag interlayer. For TiON 50/Ag 20/TiON 30 nm films, electrical resistivity decreased to as low as 3.3 × 10^− 4 Ωcm. The optical transmittance was also influenced by the Ag interlayer. As the Ag thickness increased, the optical transmittance decreased to as low as 45% for TiON 50/Ag 20/TiON 30 nm films. From observed figure of merit and work function, it is concluded that a TAgT film with a 5 nm-thick Ag interlayer is a good candidate for use as a transparent electrode in OLEDs and flat panel displays.     

Fabrication and characterization of amorphous silica nanostructures

Large-scale amorphous silica nanostructures, including nanowires, nanotubes and flowerlike nanowire bunches depending on the position, have been fabricated on silicon wafer through a cheap route under the assistance of gold and germanium. Accompanying the observation of blue-green light emission, comprehensive micro-structural characterization reveals that the growth of nanostructures is catalyzed only by gold whereas the final morphology of nanostructures depends on the location to germanium ball. Au₂Si, a compound of gold and silicon, is also disclosed as an intermediate state during the catalysis. Correspondingly, a growth scheme is proposed based on the experimental results and the vapor-liquid-solid mechanism.