Preparation of superconducting edge junctions using polymeric Langmuir–Blodgett films as barrier layers

Aromatic polyamic acid alkyl ammonium salt exhibits very good transfer behavior under suitable deposition conditions. A superconducting thin film of YBa₂Cu₃O_x (YBCO) on Langmuir–Blodgett film (LB) has been obtained when the substrate temperature is higher than 500°C. Superconducting edge junctions of (Pb—In)/LB/(Pb—In) and YBCO/LB/YBCO incorporated with polyimide LB films were fabricated. Their current–voltage characteristics are discussed in terms of the temperature stability of polyimde LB films. © 1994 John Wiley & Sons, Inc.     

Growth of nanostructured thin films of poly(p-xylylene) derivatives by vapor deposition

Nanostructured thin films of poly(p-xylylene) derivatives are deposited by oblique angle vapor deposition method under low-vacuum conditions. We showed deposition of columnar nanostructured poly(chloro-p-xylylene) and poly(bromo-p-xylylene) thin films, and co-deposition of nanostructured poly(o-trifluoroacetyl-p-xylylene-co-p-xylylene) thin film. Characterization of both the nanostructured and planar thin films of poly(p-xylylene) are performed with different experimental methods. We developed a generalized strategy towards depositing nanostructured poly(p-xylylene) derivatives and thus promise a new generation of thin films suitable for biomedical and antifouling applications.     

Self-polarized ferroelectric PVDF homopolymer ultra-thin films derived from Langmuir–Blodgett deposition

It was found that Langmuir–Blodgett (LB) deposition process led to the direct formation of ferroelectric β phase in poly(vinylidene fluoride) (PVDF) homopolymer ultra-thin films, in which the molecular chains were parallel to the substrates and the dipoles were aligned perpendicular to the substrates. Theoretical analysis and experimental results further showed that the mechanism of forming the β phase and the dipole orientation were attributed to the hydrogen bonds formed between the PVDF molecules and water through the LB deposition. A large local effective piezoelectric coefficient (d_zz) of ?49.4 pm/V was observed in the self-polarized PVDF LB film.     

Investigation of heterostructure between diamond and iridium on sapphire

Diamond thin film has outstanding physical and chemical properties. Diamond-on-iridium configurations have been prepared by several methods, such as microwave enhanced plasma CVD, direct currency plasma CVD, and hot filament CVD. In this study, an Ir interlayer was deposited on single crystal sapphires (Al₂O₃) with A-planes {1120} by an RF magnetron sputtering method after annealing samples. In addition, a diamond thin film was deposited by a microwave enhanced plasma chemical vapor deposition (MPCVD) method using a mixture of hydrogen and methane gases after a bias enhanced nucleation (BEN) procedure.Ir (001) was grown on the A-plane of sapphire by X-ray pole figure measurement. Diamond thin films were synthesized on each Ir/sapphire substrate and characterized by SEM, Raman spectroscopy. D {100} faces were exhibited in substantial areas of diamond films, and a flat D {100} plane was partially obtained. It is considered that diamond thin films on Ir {100} were mainly grown towards the <100> direction and were epitaxially grown in part.     

Mechanism of polysilazane thin film formation during glow discharge polymerization of hexamethylcyclotrisilazane

Preparation of thin polymer films by the glow discharge polymerization of hexamethylcyclotrisilazane has been studied. The effect of basic parameters of the process, such as time, pressure and current density on the polymer deposition kinetics has been established. It has been found that the curves of polymer deposition rate versus monomer vapour pressure have the same shape as the adsorption isotherms. The experimental relationships R = f(p) have been analysed by means of the adsorption equations BET and HJ. A good agreement between the experimental results and adsorption equations suggests an adsorption mechanism of the polysilazane film formation. The effect of polymerization conditions on the properties and morphology of thin polysilazane films has been also investigated.     

Characterization of polymeric LB thin films for sensor applications

The Quartz Crystal Microbalance (QCM) system is utilized to investigate the relationship between mass uptake and associated swelling for Langmuir‐Blodgett (LB) organic thin films obtained from pyrene end‐capped polystyrene (PS). The study was carried out using three different molecular weights of polymeric chains. The changes in resonance frequency associated with mass changes can be attributed to the swelling behavior of polymeric thin films during vapor absorption. This swelling is due to the capturing of organic vapor molecules in the sensor environment. To quantify real‐time QCM data for swelling, early‐time Fick's law of diffusion was adopted to fit the results, and a good linear relationship was observed between the mass uptake and square root of the swelling time. The diffusion coefficients for swelling were thus obtained from the slopes of the fitting curves and was found to be correlation with the amount of organic vapor content in the cell. It was also observed that diffusion of the organic vapor into higher molecular weight polystyrene thin films are much faster than low molecular weight ones in sensor applications. Diffusion coefficients were found to be 0.2–3.0 × 10^?16, 5.0–13 × 10^?16, and 1.0–1.6 × 10^?15 cm²/s for PS1, PS2, and PS3 LB thin films, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Langmiur–Blodgett studies of silicon(IV) phthalocyanine bis(trihexylsilyoxide) and its optical properties

Although much solution-based research has been carried out on silicon phthalacyanines, little work has been done on Si Pc LB films. In order to attempt studies on thin films, ultrathin Langmuir–Blodgett films of silicon(IV) phthalocyanine bis(trihexylsilyoxide), C₆₈H₉₄N₈O₂Si₃ have been studied and characterised. Whilst silicon(IV) phthalocyanine bis(trihexylsilyoxide) is not a traditional LB film forming material, it can be made conducive to deposition by mixing with ideal film forming materials such as calixarenes. Surface pressure–area isotherms revealed an area per molecule of around 7.5 Å² which indicates that the silicon(IV) phthalocyanine bis(trihexylsilyoxide) forms multi-lamella stacks. Thermal optical polarised spectroscopy revealed the formation of brightly coloured mesophases in films. DSC showed the presence of an irreversible A phase and a reversible T phase.     

Gadolinia Doped Ceria Thin Films Prepared by Aerosol Assisted Chemical Vapor Deposition and Applications in Intermediate‐Temperature Solid Oxide Fuel Cells

Furthermore, deposition at such low temperatures is promising for processing of thin film assemblies. The preparation of bi‐layer electrolytes of yttria stabilized zirconia and gadolinia doped ceria thin films by aerosol assisted chemical vapor deposition is demonstrated. Gadolinia doped ceria films as thin as 150 nm are applied as barrier layers between yttria stabilized zirconia electrolyte and La_0.6Sr_0.4CoO_3–δ cathode in anode supported solid oxide fuel cells. High power densities above 850 mW cm^–2 at 650 °C are only obtained with these barrier layers, indicating that the GDC thin films effectively inhibit the formation of unwanted interface reactions.     

Fabrication of a new type of organic-inorganic hybrid superlattice films combined with titanium oxide and polydiacetylene

We fabricated a new organic-inorganic hybrid superlattice film using molecular layer deposition [MLD] combined with atomic layer deposition [ALD]. In the molecular layer deposition process, polydiacetylene [PDA] layers were grown by repeated sequential adsorption of titanium tetrachloride and 2,4-hexadiyne-1,6-diol with ultraviolet polymerization under a substrate temperature of 100°C. Titanium oxide [TiO₂] inorganic layers were deposited at the same temperatures with alternating surface-saturating reactions of titanium tetrachloride and water. Ellipsometry analysis showed a self-limiting surface reaction process and linear growth of the nanohybrid films. The transmission electron microscopy analysis of the titanium oxide cross-linked polydiacetylene [TiOPDA]-TiO₂ thin films confirmed the MLD growth rate and showed that the films are amorphous superlattices. Composition and polymerization of the films were confirmed by infrared spectroscopy. The TiOPDA-TiO₂ nanohybrid superlattice films exhibited good thermal and mechanical stabilities.     

纳米二氧化钛薄膜制备方法研究进展

二氧化钛纳米晶薄膜优异的性能使其成为研究焦点,制备二氧化钛薄膜有着重要的现实意义。介绍了近年来国内外二氧化钛薄膜制备技术的研究进展,主要涉及高活性二氧化钛光催化薄膜的制备(制备方法包括溶胶-凝胶法、丝网印刷法、激光化学气相沉积法、水热结晶法、电泳法等),负载二氧化钛薄膜常用的载体,以及在环境保护等方面的应用研究现状,并指出以后的研究方向。     

Effect of surface charges on the polarization of BaTiO3 thin films investigated by UHV‐SPM

Nanostructured BaTiO₃ polar thin films are increasingly critical to the function of future multilayer ceramic capacitors and related oxide‐based electronic devices. The effect of surface charges on BaTiO₃ polarization behavior is therefore investigated by ultra‐high vacuum scanning probe microscopy (UHV‐SPM) for 3 distinct morphologies—epitaxial, polycrystalline, and nanocrystalline films. Regardless of the film morphology, Kelvin probe force microscopy reveals that BaTiO₃ thin film surfaces exhibit positive charging after contact scanning by various noble AFM probes due to the work function difference between tip and specimen. According to piezoresponse force microscopy, these positive charges uniformly stabilize downward polarized domains. However, the hysteresis and concomitant surface charging behavior are strongly sensitive to microstructure and defects. In particular, the stability and switching behavior are influenced by bulk and interfacial defect distributions and hence correlated to film deposition methods and grain size. Such morphology dependent properties for BaTiO₃ films are revealed only through UHV measurements where screening charges from the ambient can be minimized, demonstrating the importance of UHV‐SPM for understanding ferroelectric thin films and nanostructures.     

物理气相沉积（PVD）硬质薄膜及在工模具上的应用

材料的磨损、腐蚀及其它环境损伤是机械工业面临的基本问题之一，近年来，由离子参与和等离子体增强的各种气相沉积技术为解决这一问题提供了有效的途径。物理气相沉积（PVD）是制备硬质薄膜的主要方法之一，许多技术已实现工业化生产。本文综述了物理气相沉积技术制备的各种机械功能薄膜的性能及在工模具上的应用情况。     

LB膜技术的应用研究进展

LB膜技术是在分子水平上制备有序分子超薄膜的先进技术。对LB膜技术的研究和应用进行了综述，介绍了目前LB技术在实现超微细粒子的二维有序组装，在光学，电化学器件和气体传感器中的应用以及通过LB膜技术组装生物仿生膜等方面的最新研究成果。     

Novel Langmuir–Blodgett film with ternary europium complex of long chain mono-eicosyl cis-butene dicarboxylate and 1,10-phenanthroline: Cooperative assembly and luminescence

Maleic anhydride is modified by two long chain alcohol (1-hexadecanol, 1-octadecanol) to the corresponding monohexadecyl cis-butene dicarboxylate (MAH) and monooctadecyl cis-butene dicarboxylate (MAO), respectively. Then the two ternary europium complexes with the as-derived long chain monoester and 1,10-phenanthroline (Phen) are synthesized and characterized. Furthermore the ultra thin luminescent Langmuir–Blodgett (LB) films have been prepared by using the subphase containing Eu³⁺ by the film-formation ability of long chain monoester, whose luminescence has been sensitized by phen. The layer structure of the LB films is demonstrated by low-angle X-ray diffraction and the AFM study reveals that the LB films are uniform and crack free, and the films mainly consist of closely packed lines or stripes. The LB films present characteristic luminescence of Eu³⁺, and the signal can be detected from a single layer.     

Control of polymerization processes of 10,12-pentacosadiynoic acid LB films

Studies have been carried out on KrF excimer laser light (EX), X-ray or electron beam (EB) induced polymerization of 10,12-pentacosadiynoic acid (PDA) Langmuir-Blodgett (LB) films in relation to molecular density or molecular arrangement of the films using X-ray diffraction analysis, infrared (IR) spectroscopy and Raman spectroscopy. The molecular arrangement or density of the PDA LB films was controlled by subphase conditions when the films were built up, such as pH, temperature of a subphase or salt concentration in the subphase. Polymerization sensitivity of the PDA LB film was affected by the arrangement or molecular density. On low density (A type) films the polymerization occurred by irradiation with EX, X-ray or EB, but on high density (B type) films the polymerization occurred only when the irradiation was carried out by high energy beams such as X-ray or EB. Decomposition of polymerized films was observed further by excessive irradiation of EX or X-ray, but not on the B type films. It was revealed by X-ray diffraction analysis that in the A type film, the PDA molecules bent to a larger extent than those in the B type film and the polymerization proceeded topochemically, that is, the thickness decreased little after EB irradiation in a helium atmosphere. On the other hand, in the B type film, the thickness decreased by about 10% as a result of EB irradiation. By IR reflection-absorption (RA) and Raman measurements, it was confirmed that conjugated diacetylenic bonds disappeared and conjugated double and new conjugated triple bonds appeared after high energy beam irradiations. These results support the supposition that 1,4-polymerization, i.e. polydiacetylene type polymerization, occurs easily in the A type film and 1,2- or 3,4-polymerization, i.e. polyacetylene type polymerization, occurs in the B type film, and that the polymerized A type film was decomposed at the polydiacetylenic bond when the irradiation continued further. It was also shown that the polyacetylene type polymer was obtained only when the B type film was irradiated with the high energy beam.     

Characterization of the biaxial textures of MgO thin films grown by E-beam evaporation

The biaxial textures of MgO thin films with thicknesses 4500–5500 Å deposited by electron beam evaporation on glass substrates have been characterized. The surface normal to the amorphous soda-lime glass substrate was placed parallel to the MgO vapor flux, i.e., at zero degree with respect to the MgO vapor source. The MgO thin films showed biaxial texture regardless of the deposition parameters. XRD and SEM have been used to characterize the crystal structure and thin film surface morphology. In this study we devised a novel method for the characterization of the biaxial texture of MgO thin films with thicknesses ≤5000 Å, for which the X-ray pole figure method cannot be used due to the low scattering intensity from the MgO film containing only low atomic X-ray scattering ions. We report the biaxial texture development in MgO thin films grown by E-beam evaporation on the amorphous glass substrate inclined at zero degree with respect to the MgO vapor source.     

Nucleation and growth behavior of aluminum nitride film using thermal atomic layer deposition

Aluminum nitride (AlN) film possesses wide band gap energy (~6.2 eV) and a high dielectric constant (~9.2), and is resilient to thermal and chemical stimuli. It also exhibits several functionalities, such as piezoelectricity and pyroelectricity. Therefore, AlN film has been used for electronic and optoelectronic devices and micro-electromechanical systems (MEMSs). Among the various methods of AlN thin film growth, atomic layer deposition (ALD) can control film thickness at the nanoscale. Uniform and conformal film growth is possible at temperatures lower than that of chemical vapor deposition or molecular beam epitaxy. Because the ALD process relies on surface chemical reactions, it shows substrate dependency. To control film uniformity from the beginning, an understanding of nucleation and growth behavior on the substrate is necessary. Therefore, the nature of nucleation and growth behaviors on different substrates is investigated. In this study, AlN films are grown on bare Si and TiN substrates at 295–342 °C by thermal ALD using trimethyl aluminum (TMA) and ammonia. Facile nucleation and linear growth on the TiN substrate, and substrate-inhibited nucleation on the Si substrate, are observed. NH₃ pretreatment may enhance the growth rate at the nucleation stage. Therefore, the dissociation of NH₃ on the substrate is crucial to making uniform nuclei for the subsequent growth of AlN film.     

酞菁衍生物的组装改性技术及应用研究进展

酞菁及金属酞菁的改性组装可以调变其结构和特性,进而开发出多种先进的功能材料。酞菁改性的理化方法包括聚合、取代、负载等手段,技术工艺包括气相沉积法、真空镀膜法、旋涂法、电化学聚合法、相转移法、溶胶-凝胶法、LB膜技术等。除用于染料和颜料外,酞菁衍生物的应用领域主要有新型功能材料(光敏材料、气敏材料等),新型仿酶催化剂(新型脱硫催化剂、有机反应的催化剂、新型水质处理剂等)。     

基于富勒烯液态源的超纳米晶金刚石薄膜生长

通过微波等离子体化学气相沉积技术(MWPCVD),以富勒烯(C60)甲苯饱和溶液为碳源,用载气携带的方式通入反应腔中生长金刚石膜。Raman光谱、SEM和AFM表征结果表明得到的超纳米晶金刚石薄膜相组成纯度较高,其平均晶粒尺寸约为15 nm,表面粗糙度为16.56 nm,薄膜平均生长速率约为0.6μm/h。此方法较其他以C60为碳源生长超纳米晶金刚石薄膜的方法更为简便,且容易控制富勒烯碳源的浓度,沉积速率更高,是一种新型的制备超纳米晶金刚石薄膜的可控工艺方法。