Thin transparent W-doped indium-zinc oxide (WIZO) layer on glass

Annealing effect on structural and electrical properties of W-doped IZO (WIZO) films for thin film transistors (TFT) was studied under different process conditions. Thin WIZO films were deposited on glass substrates by RF magnetron co-sputtering technique using indium zinc oxide (10 wt.% ZnO-doped In2O3) and WO3 targets in room temperature. The post annealing temperature was executed from 200 degrees C to 500 degrees C under various O2/Ar ratios. We could not find any big difference from the surface observation of as grown films while it was found that the carrier density and sheet resistance of WIZO films were controlled by O2/Ar ratio and post annealing temperature. Furthermore, the crystallinity of WIZO film was changed as annealing temperature increased, resulting in amorphous structure at the annealing temperature of 200 degrees C, while clear In2O3 peak was observed for the annealed over 300 degrees C. The transmittance of as-grown films over 89% in visible range was obtained. As an active channel layer for TFT, it was found that the variation of resistivity, carrier density and mobility concentration of WIZO film decreased by annealing process.     

Deposition and modification of titanium dioxide thin films by filtered arc deposition

Thin films of titanium dioxide have been deposited on glass substrates and conducting (100) silicon wafers by filtered arc deposition (FAD). The influence of the depositing Ti⁻ energy, substrate types and substrate temperature on the structure, density, mechanical and optical properties have been investigated. The results of X-ray diffraction (XRD) showed that with increasing substrate bias, the film structure on silicon substrates changes from anatase to amorphous and then to rutile phase without auxiliary heating, the transition to rutile occurring at a depositing particle energy of about 100 eV. However, in the case of the glass substrate, no changes in the structure and optical properties were observed with increasing substrate bias. The optical properties over the range of 300–800 nm were measured using spectroscopic elliosometery, and found to be strongly dependent on the substrate bias, film density and substrate type. The refractive index values of the amorphous, anatase and rutile films on Si were found to be 2.56, 2.62 and 2.72 at a wavelength of 550 nm, respectively. The hardness and elastic modulus of the films were found to be strongly dependent on the film density. Measurements of the mechanical properties and stress also confirmed the structural transitions. The hardness and elastic modulus range of TiO₂ films were found to be between 10–18 and 140–225 GPa, respectively. The compressive stress was found to vary from 0.7 to 2.6 GPa over the substrate bias range studied. The composition of the film was measured to be stoichiometric and no change was observed with increasing substrate bias. The density of the film varied with change in the substrate bias, and the density ranged between 3.62 and 4.09 g/cm³.     

双向拉伸聚乳酸膜的制备及其性能研究

采用BarmagΦ175双向拉伸膜设备进行聚乳酸膜的制备,TGA分析表明,所购得的聚乳酸粒子具有一定的热稳定型.通过GPC测试分子量及其分布表明,聚乳酸在加工过程中会有一定程度的降解;DSC分析说明,在现有的工艺条件下得到的厚膜具有较低的结晶度,有利于后期膜的双向拉伸进行,经双向拉伸后聚乳酸膜的结晶度具有较大程度的增加.DMA及力学性能测试结果表明,拉伸倍数对膜性能影响很大,拉伸倍数越高,膜的力学性能越好.     

Surface acoustic wave thermogravimetric measurements of thin polymer films

The increased use of thin film polymers in microelectronic applications has resulted in the need to better understand their chemical, thermal, mechanical, and electrical properties. Of particular interest are changes in mass and viscoelasticity during curing of new high temperature polymers. A highly sensitive technique that can monitor mass and viscoelastic changes in thin polymer films during curing to high temperature is needed. In this work a surface acoustic wave (SAW) based system was developed that was capable of measuring the mass loss due to water outgassing during cure of thin polymer films in a temperature range of 20 to 400 degrees C. It also could measure the apparent glass transition temperature of acoustically thin films, and film resonance for acoustically thick films. The principle limitations of the system are the limited accuracy of temperature compensation and the limited ability to separate mass loss effects from viscoelastic effects.     

Thickness-dependent properties of sprayed iridium oxide thin films

Iridium oxide thin films with variable thickness were deposited by spray pyrolysis technique (SPT), onto the amorphous glass substrates kept at 350 °C. The volume of iridium chloride solution was varied to obtain iridium oxide thin films with thickness ranging from 700 to 2250 Å. The effect of film thickness on structural and electrical properties was studied. The X-ray diffraction (XRD) studies revealed that the as-deposited samples were amorphous and those annealed at 600 °C for 3 h in milieu of air were polycrystalline IrO₂. The crystallinity of Ir-oxide films ameliorate with film thickness thereby preferred orientation along (1 1 0) remains unchanged. The infrared spectroscopic results show Ir–O and Ir–O₂ bands. The room temperature electrical resistivity (ρ_RT) of these films decreases with increase in film thickness. The p-type semiconductor to metallic transition was observed at 600 °C.     

X-ray diffraction investigations of α-polyamide 6 films: orientation and structural changes upon uni- and biaxial drawing

We have investigated the influence of drawing on orientation, crystallinity, and structural properties of polyamide 6 films using X-ray diffraction. The samples were uniaxially and biaxially stretched resulting in the formation of monoclinic crystallites (α-form) in the size range of 8–10 nm. Depending on the drawing ratio, a degree of crystallinity of up to 60% is obtained. The average orientation of the crystallite axes was evaluated using the pole figure technique. The b*-axis, which corresponds to the chain direction of the polyamide molecules, lies in the film plane and shows a preferred orientation upon drawing. For uniaxial drawing, b* aligns with the drawing direction. For biaxially drawn films, which were prepared using the sequential stretching method, the second drawing determines the orientation of b*, at least at the center of the films. At the sides, b* is located between the two drawing directions reflecting the inhomogeneous distribution of mechanical stress during stretching.     

Anomalous elastic properties of RF-sputtered amorphous TeO2+x thin film for temperature-stable SAW device applications.

The anomalous elastic properties of TeO2+x thin films deposited by rf diode sputtering on substrates at room temperature have been studied. The deposited films are amorphous, and IR spectroscopy reveals the formation of Te-O bond. X-ray photoelectron spectroscopy confirms the variation in the stoichiometry of TeO2+x film from x=0 to 1 with an increase in the oxygen percentage in processing gas composition. The elastic parameters of the films in comparison to the reported values for TeO2+x single crystal are found to be low. However, the temperature coefficients of elastic parameters of all deposited films exhibit anomalous behavior showing positive values for TC(C11) in the range (32.0 to 600.0)x10(-4) degrees C(-1) and TC(C44)=(35.0 to 645.5)x10(-4) degrees C(-1) against the negative values TC(C11)=-2.7x10(-4) degrees C(-1) and TC(C44)=-0.73x10(-4) degrees C(-1) reported for TeO2+x single crystal. The variation in the elastic parameters and their temperature coefficients is correlated with the change in the three-dimensional network of Te-O bonding. The anomalous elastic properties of the TeO2+x films grown in 100% O2 are useful for potential application in the design of temperature stable surface acoustic wave devices.     

Mechanical properties and scratch resistance of filtered-arc-deposited titanium oxide thin films on glass

The mechanical properties and the scratch resistance of titanium oxide (TiO₂) thin films on a glass substrate have been investigated. Three films, with crystalline (rutile and anatase) and amorphous structures, were deposited by the filtered cathodic vacuum arc deposition technique on glass, and characterized by means of nanoindentation and scratch tests. The different damage modes (arc-like, longitudinal and channel cracks in the crystalline films; Hertzian cracks in the amorphous film) were assessed by means of optical and focused ion beam microscopy. In all cases, the deposition of the TiO₂ film improved the contact-mechanical properties of uncoated glass. Crystalline films were found to possess a better combination of mechanical properties (i.e. elastic modulus up to 221 GPa, hardness up to 21 GPa, and fracture strength up to 3.6 GPa) than the amorphous film. However, under cyclic sliding contact above the critical fracture load, the amorphous film was found to withstand a higher number of cycles. The results are expected to provide useful insight for the design of optical coatings with improved contact-damage resistance.     

Highly transparent polymer substrates for flexible displays using semi-interconnected interpenetrating polymer networks

Semi-interconnected interpenetrating polymer networks (SIPNs) based on unsaturated polyurethane (UP) and different monomers, including styrene and acrylate with an UP ratio of 50 wt%, were synthesized. The resulting SIPN films exhibited excellent optical transparency in the visible range with > 90% transmittance at 400 nm. The glass transition temperature (Tg) varied in the range of 100 approximately 135 degrees C depending on the unsaturated monomers introduced. They also had good flexibility compared to the conventional rigid polystyrene or polyacrylate due to the homogeneously dispersed elastic urethane moiety in the SIPNs. Below the glass transition temperature (Tg) of the SIPN substrates, the ITO-grown SIPN films exhibited good electrical and optical properties, showing potential as a promising substrate in flexible display applications.     

Synthesis and characterization of tungsten disulphide films grown by pulsed-laser deposition

The synthesis and characterization of tungsten disulphide (WS₂) films grown on 440C stainless steel substrates using the 248 nm line from a KrF excimer laser are reported. Film properties could be adjusted by controlling substrate temperature and by laser or thermal anneals. X-ray photoelectron spectroscopy, glancing angle XRD, Raman spectroscopy and high-resolution scanning electron microscopy were used to evaluate film chemistry, crystallinity and morphology. Films grown at room temperature were amorphous, near stoichiometric, and had a multiplicity of chemical states. Local order and bonding were improved most dramatically through post-deposition laser anneals. Crystallite size could be increased by raising the substrate temperature during deposition and, to a lesser degree, by post-deposition thermal anneals. Local disorder was observed within the larger crystallites compared to those that were laser annealed. Crystallinity was induced in amorphous films by mechanical rubbing at room temperature under conditions where frictional heating was negligible. The degree of control over film properties provided by PLD demonstrates its value for growing/designing tribological coatings.     

Mechanical properties of blends of poly(methyl methacrylate) and poly(vinylidene fluoride)

The mechanical properties of blends of the crystallizable polymer poly(vinylidene fluoride) and the amorphous material poly(methyl methacrylate) have been investigated as a function of composition both for glassy amorphous materials and for partially crystalline materials. The data obtained were interpreted in terms of the molecular and super-molecular structure of the blends and in terms of their dynamic properties.The main conclusions were that the mechanical properties are not strongly dependent on details of the distribution of the two components in the material nor on the crystal modifications present. The mechanical properties were found to depend primarily on the location of the glass transition temperature relative to the elongation temperature and on the presence or absence of crystalline regions. The degree of crystallinity was found to play an important role in determining the properties only at lower values of this quantity. The advantage of these blends is that the important parameters, namely, the degree of crystallinity and the location of the glass transition temperature, can be adjusted at will by varying the composition appropriately. This allows well-defined variations of the mechanical properties to be achieved.     

Influence of heat treatment and particle shape on mechanical properties of infiltrated Al2O3 particle reinforced Al–2 wt-% Cu

Abstract

Carbon dioxide (CO₂) generation by ultraviolet irradiation of poly(ethyleneterephthalate) (PET) films in oxygen was monitored by in situ Fourier transform infrared spectroscopy. Typically, the CO₂ absorbance increased by ～100 × 10^?4 in 180 min, with no evidence of hindrance by restricted diffusion of O₂ into, or CO₂ out of, the films. It was concluded that Fourier transform infrared spectrometry monitoring of CO₂ conveniently, reliably and rapidly measures PET films photostability.

Quantitative analysis of the CO₂ evolved from progressively thinner films from successive stages of the biaxial film drawing process indicated that CO₂ was generated within a few microns of the film surface and that the same amounts were generated from the irradiated surface of 540 μm cast, 150 μm uniaxially drawn and 85 μm biaxially drawn films. Although drawing increased film crystallinity, photoreactivity appeared to be unchanged. However, total CO₂ formation followed the pattern PET cast相似文献   

High-strength and high-modulus poly(vinyl alcohol) by the gel-ageing methodPart II The effect of the gel pressing temperature

It was reported in our previous paper that a relatively high-strength and high-modulus drawn poly(vinyl alcohol) (PVA) film could be obtained from aged gel sheet. In this paper, the effect of pressing temperature, at which the original PVA/dimethylsulphoxide/water gel was pressed into the gel sheet, on the tensile properties (modulus and strength) of the finally obtained drawn film is reported. The properties of the drawn films are discussed in relation to the structure of the undrawn films and the gel sheet, by birefringence and molecular orientation measurements, differential scanning calorimetry, and X-ray diffraction methods. As a result, the content of the low melting-temperature crystal component in the pressed gel is shown to be the most effective factor affecting the properties of the drawn film. © 1998 Chapman & Hall     

Magnetic properties of Fe---SiO films

The results of an experimental investigation of the magnetic properties of Fe_100−x(SiO)_x cermet thin films (where x is the volume percentage of SiO in the film) in the concentration range 10 vol.% x 93 vol.% are given. The films were synthesized using the vacuum deposition method. Films with a sufficiently large SiO content (x 25–40 vol.%) are amorphous and display a number of new properties. A T−x phase diagram of the ferromagnet-superparamagnet transition was obtained. A transition to the cluster glass state was found at low temperatures and fields. The correlation radius of the exchange parameter fluctuations was determined from measurements of the spin wave resonance at a number of concentrations.     

Temperature dependence of the magnetic properties of amorphous Co-Gd-Mo thin films

RF sputter deposited amorphous Co-Gd-Mo thin films have previously been shown to be potential materials for bubble device applications. However, the operation of a bubble device over a realistic temperature range requires materials with magnetic properties which are relatively temperature insensitive. An assessment of the temperature dependence of the magnetic properties of amorphous Co-Gd-Mo films is reported. The results of a mean field analysis of the magnetization data of Co-Gd-Mo thin films over wide composition and temperature ranges allowed optimization of the film composition for obtaining most suitable temperature dependences of magnetic properties. It has been found that even with the optimum compositions, the degree of temperature insensitivity improves with decreasing bubble diameters and is satisfactory only for sub-half-micron bubble materials. These results and analysis suggest that similar qualitative behavior may also be expected for other transition metal-rare earth alloys.     

N-type crystalline silicon films free of amorphous silicon deposited on glass by HCl addition using hot wire chemical vapour deposition

Since n-type crystalline silicon films have the electric property much better than those of hydrogenated amorphous and microcrystalline silicon films, they can enhance the performance of advanced electronic devices such as solar cells and thin film transistors (TFTs). Since the formation of amorphous silicon is unavoidable in the low temperature deposition of microcrystalline silicon on a glass substrate at temperatures less than 550 degrees C in the plasma-enhanced chemical vapour deposition and hot wire chemical vapour deposition (HWCVD), crystalline silicon films have not been deposited directly on a glass substrate but fabricated by the post treatment of amorphous silicon films. In this work, by adding the HCl gas, amorphous silicon-free n-type crystalline silicon films could be deposited directly on a glass substrate by HWCVD. The resistivity of the n-type crystalline silicon film for the flow rate ratio of [HCl]/[SiH4] = 7.5 and [PH3]/[SiH4] = 0.042 was 5.31 x 10(-4) ohms cm, which is comparable to the resistivity 1.23 x 10(-3) ohms cm of films prepared by thermal annealing of amorphous silicon films. The absence of amorphous silicon in the film could be confirmed by high resolution transmission electron microscopy.     

Temperature effects on resistance of aligned multiwalled carbon nanotube films

Electrical transport in vertically aligned films of multiwalled carbon nanotubes has been investigated in the -150 degrees C to 300 degrees C temperature range (all the tests were conducted in air at atmospheric pressure). In all the cases, the nanotube film exhibited a semi-conducting behavior, with the film resistance decreasing with increasing temperature. Removal of amorphous carbon contamination (via plasma etching) significantly improved the nanotube film's sensitivity to temperature changes (particularly in the 20 degrees C to 200 degrees C temperature range). All the of films tested in this study showed a consistent, repeatable behavior that was independent of the nanotube film length. The temperature sensitivity of the nanotube films was also found to be independent of the heating/cooling rates and without hysteresis. Because of the excellent repeatability and stability of the results, it is conceived that miniaturized temperature sensors could be designed using such aligned multiwalled nanotube films.     

Co-sedimentation of TiO2 nanoparticles and polymer beads to fabricate macroporous TiO2 photoelectrodes

Dye-sensitized solar cells based on highly porous nanocrystalline TiO2 films have drawn considerable attention due to their high conversion efficiency and low production cost. TiO2 nanocrystalline electrodes have been investigated extensively as a key material. In this study, we discuss dye-sensitized solar cells based on macroporous TiO2 films using a highly-dispersed aqueous solution of TiO2 nanoparticles and polymeric particles. After drying this solution on the conducting glass substrate, the sacrificial polymer particles were removed selectively by thermal sintering at high temperatures over 400 degrees C or chemical treatment at the low temperature of 150 degrees C. This method provides the flexible control of TiO2 fractions or pore size or fabrication temperature. Also highly-dispersed TiO2 particles with a high crystallinity would provide a promising solution on low-temperature process for flexible DSSCs.     

Influence of filament-to-substrate distance on the spectroscopic,structural and optical properties of silicon carbide thin films deposited by HWCVD technique

Silicon carbide (SiC) thin films were deposited using hot wire chemical vapor deposition (HWCVD) technique from pure silane and methane gas mixture. The effect of filament distance to the substrate on the structural and optical properties of the films was investigated. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman scattering spectroscopy and UV–Vis–NIR spectroscopy were carried out to characterize SiC films. XRD patterns of the films indicated that the film deposited under highest filament-to-substrate distance were amorphous in structure, while the decrease in distance led to formation and subsequent enhancement of crystallinity. The Si–C bond density in the film structure obtained from FTIR data, showed significant increment with transition from amorphous to nano-crystalline structure. However, it remained almost unchanged with further improvement in crystalline volume fraction. From Raman data it was observed that the presence of amorphous silicon phase and sp ² bonded carbon clusters increased with the decrease in distance. This reflected in deterioration of structural order and narrowing the optical band gap of SiC films. It was found that filament-to-substrate distance is a key parameter in HWCVD system which influences on the reactions kinetics as well as structural and optical properties of the deposited films.     

Plasma enhanced chemical vapor deposition of nanocrystalline silicon films from SiF4-H2-He at low temperature

A high degree of crystallinity is obtained in nc-Si:H films deposited by r.f. PECVD, produced from SiF₄-H₂-He mixtures. The amorphous-to-nanocrystalline transition is favored because of the presence of F atoms, which preferentially etch the amorphous phase. The addition of He to the SiF₄-H₂ gas mixture gives an increase of F and H atoms in the plasma, thus inducing higher crystallinity. A further improvement in the nc-Si:H film structure and properties is obtained by adjusting the r.f. power and the deposition temperature. Under optimized plasma conditions, substrate temperatures as low as 120°C can be reached for the deposition of nc-Si:H having 100% of crystallinity.