Theory of the radiation pressure on dielectric surfaces

The radiation pressures exerted by light beams incident normally on dielectric surfaces are calculated by evaluation of the quantum-mechanical Lorentz force. The free-space surface of an almost transparent dielectric and the interface of a lossy dielectric with a transparent medium are treated in detail. Light beams in the forms of a short single-photon pulse and a continuous-mode narrow-band coherent excitation are considered. The use of a pulse excitation enables discrimination of the surface and bulk contributions to the force. It is shown that the surface force is directed inwards to the dielectric for entrance and exit of the pulse from and to free space, contrary to the conclusions of some earlier work. For the interface of lossy and transparent dielectrics, it is shown that the high-reflectivity mirror modelled by an appropriate limit of the lossy dielectric experiences a force enhanced by the refractive index of the transparent medium, in agreement with experiments on a mirror suspended in liquid dielectrics. The results for the Lorentz force are used to identify the effective momenta of photons in dielectrics.     

Silicate formation at the interface of Pr-oxide as a high-K dielectric and Si(001) surfaces

The composition and chemical bonding of the first atoms across the interface between Si(001) and the dielectric determine the quality of dielectric gate stacks. An analysis of that hidden interface is a challenge as it requires both, high sensitivity and elemental and chemical state information. We used X-ray absorption spectroscopy in total electron yield and total fluorescence yield at the Si2p and the O1s edges to address that issue. We report on results of Pr₂O₃/Si(001) as prepared by both, epitaxial growth and metal organic chemical vapor deposition (MOCVD), and compare to the SiO₂/Si(001) system as a reference. We find evidence for the silicate formation at the interface as derived from the characteristic features at the Si2p and the O1s edges. The results are in line with model experiments in which films of increasing film thickness are deposited in situ on bare Si(001) surfaces.     

Microstructure and growth mechanism of Cu ramified aggregates on silicone oil surfaces

We study the microstructure and growth mechanism of copper (Cu) ramified aggregates by the optical microscopy and atomic force microscopy. We find that the ramified Cu aggregates exhibit a granular structure with mean size of the single particulate in the range of 30-60 nm. It is interesting that the average width of the ramified aggregates and the mean size of the particulates do not change obviously with the increase of the nominal film thickness. Compared the size distributions of the Cu particulates on the oil surfaces with that of Cu films on glass surfaces, we suggest that the surface morphology and microstructures of Cu aggregates (or films) depend on property of substrates. The interpretation for this phenomenon is also presented.     

Minimizing light reflection from dielectric textured surfaces

In this paper, we consider antireflective properties of textured surfaces for all texture size-to-wavelength ratios. Existence and location of the global reflection minimum with respect to geometrical parameters of the texture is a subject of our study. We also investigate asymptotic behavior of the reflection with the change of the texture geometry for the long and short wavelength limits. As a particular example, we consider silicon-textured surfaces used in solar cells technology. Most of our results are obtained with the help of the finite-difference time-domain (FDTD) method. We also use effective medium theory and geometric optics approximation for the limiting cases. The FDTD results for these limits are in agreement with the corresponding approximations.     

Bias stress effects on different dielectric surfaces of pentacene thin-film transistors

In this paper, it was demonstrated that pentacene thin-film transistors (TFTs) were fabricated with an organic adhesion layer between an organic semiconductor and a gate insulator. In order to form polymeric film as an adhesion layer, a vapor deposition polymerization (VDP) process was introduced to substitute for the usual spin-coating process. Field effect mobility, threshold voltage, and on/off current ratio in pentacene TFTs with a 15 nm thick organic adhesion layer were about 0.4 cm2/Vs, -1 V, and 10(6), respectively. We also demonstrated that threshold voltage strongly depends on the stress time when a gate voltage has been applied for bias stress test. We suggest that a polyimide adhesion layer fabricated by the VDP method can be applied to realize organic TFTs with long-term stability because of lower threshold voltage shifts due to reduced charge trapping at the interface between the pentacene semiconductor and the polyimide layer.     

Controlled effect of ultrasonic cavitation on hydrophobic/hydrophilic surfaces

Controlling cavitation at the solid surface is of increasing interest, as it plays a major role in many physical and chemical processes related to the modification of solid surfaces and formation of multicomponent nanoparticles. Here, we show a selective control of ultrasonic cavitation on metal surfaces with different hydrophobicity. By applying a microcontact printing technique we successfully formed hydrophobic/hydrophilic alternating well-defined microstructures on aluminium surfaces. Fabrication of patterned surfaces provides the unique opportunity to verify a model of heterogeneous nucleation of cavitation bubbles near the solid/water interface by varying the wettability of the surface, temperature and ultrasonic power. At the initial stage of sonication (up to 30 min), microjets and shock waves resulting from the collapsing bubbles preferably impact the hydrophobic surface, whereas the hydrophilic areas of the patterned Al remain unchanged. Longer sonication periods affect both surfaces. These findings confirm the expectation that higher contact angle causes a lower energy barrier, thus cavitation dominates at the hydrophobic surfaces. Experimental results are in good agreement with expectations from nucleation theory. This paper illustrates a new approach to ultrasound induced modification of solid surfaces resulting in the formation of foam-structured metal surfaces.     

Controlled deposition of gold nanowires on semiconducting and nonconducting surfaces

One of the pressing problems in advancing nanoelectronic applications and systems is to develop a simple means of freely connecting at a nanometric level electronic components under ambient conditions without the need for vacuum or electron or ion beam operational steps. Such environments may have detrimental effects on the molecular or biomolecular constituents of molecular electronic circuits. Although there has been defined progress in connecting structures that are of nanometric dimension, new methods in this area of nanotechnology with general applicability add to the arsenal of tools for addressing this standing problem. This paper addresses freely placing under ambient conditions, with fountain pen nanolithography, a 120 nm dimension line of gold nanocolloids deposited with precise registration in a 100 nm gap between two 250 nm wide conducting electrodes patterned by electron beam lithography.     

Mechanical properties of nanoparticle chain aggregates by combined AFM and SEM: isolated aggregates and networks

Mechanical properties of nanoparticle chain aggregates (NCA) including tensile strength and Young's modulus were measured using an instrument incorporating an AFM tip under SEM imaging. The NCA were studied individually and as network films. Carbon NCA were made by laser ablation of graphite, and SnO2 NCA were made by oxidation of a tin compound. The films were deformable and showed elastic behavior. NCA serve as reinforcing fillers in rubber and films of SnO2 NCA for trace gas detection.     

Effect of dielectric barrier discharge on wing-tip vortex formation

The formation of vortex trace behind a finite-span model airfoil has been studied by the method of stereoscopic particle image velocimetry. It is established that a dielectric barrier discharge initiated at the airfoil tip surface influences the wing-tip vortex formation.     

Light scattering by randomly rough isotropic dielectric surfaces

Abstract

An experimental investigation of the angular distribution of the light scattered by randomly rough, two-dimensional, isotropic dielectric surfaces is presented. The surfaces, whose profiles constitute good approximations to Gaussian random processes with Gaussian correlation functions, are fabricated in a photoresist and characterized by means of a mechanical profilometer. The substrates employed in the fabrication of the samples consist of thick parallel plates of filter glass that absorb the incident light and whose refractive index is close to that of the photoresist. This allows us to approximate experimentally a situation in which the light is scattered by a randomly rough interface between two semi-infinite dielectric media, illuminated from the air side. The results display features that can be attributed to multiple scattering. In particular, significant amounts of cross-polarized scattered light, as well as an enhanced backscattering peak, were observed in the scattering measurements.     

Macrophage interactions with modified material surfaces

An understanding of the biological response at material surfaces is a key biomaterials research area. Inflammation, tissue repair and regeneration are hallmarks of this response. Macrophages are long-lived and versatile cells and have a pivotal role at surfaces of implanted medical devices. The present review provides an update on macrophage behaviour at material surfaces. The interactions between cells and material surfaces are dynamic processes which require additional experimental models with different degrees of environmental complexity. It is concluded that both modifications of material surface properties and cellular signalling pathways will provide strategies for optimising the performance of biomedical devices.     

Generation of focused electric field patterns at dielectric surfaces

We here report on a concept for creating well-defined electric field gradients between the boundaries of capillary electrode (a capillary of a nonconducting material equipped with an interior metal electrode) outlets, and dielectric surfaces. By keeping a capillary electrode opening close to a boundary between a conducting solution and a nonconducting medium, a high electric field can be created close to the interface by field focusing effects. By varying the inner and outer diameters of the capillary, the span of electric field strengths and the field gradient obtained can be controlled, and by varying the slit height between the capillary rim and the surface, or the applied current, the average field strength and gradient can be varied. Field focusing effects and generation of electric field patterns were analyzed using finite element method simulations. We experimentally verified the method by electroporation of a fluorescent dye (fluorescein diphosphate) into adherent, monolayered cells (PC-12 and WSS-1) and obtained a pattern of fluorescent cells corresponding to the focused electric field.     

基于LabVIEW的介电材料电阻温度特性测控系统

介绍了在LabVIEW环境下开发测试程序VI（虚拟仪器）测试片状元件试样的方阻、电阻率以及电阻温度系数TCR随温度的变化关系，主要包括电阻温度特性测控系统的硬件构成，基于IabVIEW开发平台的测控软件框图及测试程序。该测试系统在-20℃～120℃温度范围内能够实现对元件试样的多点测试，升温方法采取线性升温，且升温速率可在0．1℃／min～10℃／min之间选择，测试结果对于介电材料性能的研究以及元器件开发都有一定的价值。     

材料表面抗空蚀涂层的研究进展

空蚀现象广泛存在于海洋平台、船舶机械和能源发电等领域.这种腐蚀现象不仅造成了巨大的经济损失,也成为相关从业人员的安全隐患.本文概述了抗空蚀涂层材料技术的研究进展,重点介绍了抗空蚀金属涂层技术和抗空蚀聚合物涂层技术.最后对目前抗空蚀材料存在的问题及未来发展进行了展望.     

The effect of electrode material on the efficiency of dielectric barrier discharge

The influence of the electrode material on the specific thrust of a synthetic jet based on the dielectric barrier discharge generated by a symmetric actuator has been studied taking into account the ionization energy and resistivity of the material. Dependences of the specific thrust on the distance between outer (exposed) electrodes made of copper, aluminum, and nickel are compared.     

氧化剂对聚吡咯复合材料介电性能的影响

为了探究氧化剂对聚吡咯复合材料介电性能的影响,以吡咯为单体,采用原位聚合法制备了聚吡咯涂层复合材料。通过BDS50介电谱仪研究了氧化剂种类和氧化剂物质的量浓度对复合材料介电常数实部、虚部、损耗角正切、表面电阻的影响;采用Quanta200型环境扫描电子显微镜和Instron万能材料试验机研究了聚吡咯涂层复合材料的外观形貌和强度。结果表明:氧化剂种类、氧化剂浓度对聚吡咯涂层复合材料介电常数实部、虚部、损耗角正切、表面电阻影响较大;制备的聚吡咯涂层复合材料既具备良好的介电性能和导电性,又兼具良好的强度.     

Characterization of the dielectric properties of covalently attached organic films on silicon surfaces

Monolayers of methyl-undecanoate were constructed on silicon surfaces via a covalent Si-C bond. The molecular monolayers were characterized by high resolution electrical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and ellipsometry and displayed a densely packed monolayer. After formation of the monolayer, the methyl ester was hydrolyzed without noticeable change in the integrity of the monolayer. The carboxyl terminated organic layer was then reacted with (1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide to form active N-hydroxy succinimide ester groups. The activation chemistry was confirmed by XPS and the substructure of the methyl-undecanoate carboxylic acid and the N-hydroxy succinimide ester terminated films were characterized using EIS. XPS and EIS spectra provided information on the chemical composition and substructure of the monolayers for each step in the chemical modification of the surface.     

Localized material growth by a dielectric barrier discharge

In this paper, we have reported a localized material growth method by dielectric barrier discharge (DBD) in a mixture of acetylene and argon. We found that, in the discharge, plasma polymerization takes place and the material growth rate is much higher along the discharge filaments than it is in other locations. Three layers of material, which correspond to three modes of discharge, are observed after the plasma polymerization. One layer is homogeneous, which corresponds to a glow-like discharge. The second layer is made of small and dense columns, which can be seen only under microscope, and this layer of material's growth corresponds to a corona-like discharge. The third layer is made of a few bigger columns, which can be seen visually, and they are grown along patterned discharge streamers. By scanning electron microscope (SEM), we see that the bigger columns are made of small ball-like material with the diameter of approximately 0.1 μm. A Fourrier transfer infra-red (FTIR) spectrum of the deposited material is also shown to confirm the polymerization.