硅基图案化HfO2表面微结构的制备和表征

结合光刻印技术和HfO2液相自组装沉积成膜技术,在单晶硅表面成功地制备了具有微米级图案结构的HfO2薄膜,该硅基图案化HfO2微结构近来在工业界特别是微电子领域引起极度的关注.X射线衍射(XRD)与扫描电镜(SEM)显示,在图案区域成功制备了HfO2薄膜,EDS能谱测试显示了图案区域的HfO2薄膜的化学组成.     

Chemical tailoring of hybrid sol-gel thick coatings as hosting matrix for functional patterned microstructures

A phenyl-based hybrid organic - inorganic coating has been synthesized and processed by hard X-ray lithography. The overall lithography process is performed in a two-step process only (X-rays exposure and chemical etching). The patterns present high aspect ratio, sharp edges, and high homogeneity. The coating has been doped with a variety of polycyclic aromatic hydrocarbon functional molecules, such as anthracene, pentacene, and fullerene. For the first time, hard X-rays have been combined with thick hybrid functional coatings, using the sol-gel thick film directly as resist. A new technique based on a new material combined with hard X-rays is now available to fabricate optical devices. The effect due to the high-energy photon exposure has been investigated using FT-IR and Raman spectroscopy, laser scanner, optical profilometer, and confocal and electron microscope. High-quality thick hybrid fullerene-doped microstructures have been fabricated.     

Collecting electrospun nanofibers with patterned electrodes

Electrospinning is a simple, versatile, and useful technique for fabricating nanofibers from a rich variety of functional materials. The nanofibers are usually collected as nonwoven mats, in which the fibers are randomly oriented. We have recently demonstrated that the nanofibers can be uniaxially aligned by introducing an insulating gap into the conductive collector. To elucidate the mechanism of alignment, we have systematically studied the effect of the area and geometric shape of the insulating gap on the deposition of fibers. By modeling the electrostatic forces acting on the fiber, it was established that the fibers tended to be oriented along a direction such that the net torque of electrostatic forces applied to the two ends of a discrete segment of the fiber were minimized. By varying the design of electrode pattern, it was possible to control both alignment and assembly of the electrospun nanofibers.     

亚表面缺陷的实时成像检测

提出一种适合于金属亚表面缺陷的可视化无损检测方法——磁光/脉冲涡流成像方法。该方法以脉冲信号激励产生涡流,以激光对被检测物体的照射取代传统涡流检测的线圈探头,通过磁光传感元件将缺陷引起的磁场变化转换成相应的光强度的变化,由传统的显微镜、照明系统、偏振器和CCD图像传感器组成的光学系统将光强变化转换为“明”或“暗”图像,实现了对缺陷的实时成像检测。本文论述了磁光/脉冲涡流实时成像检测机理,给出了一种实验装置。通过对金属表面/亚表面缺陷实验,表明该检测方法快速、准确,可实现微/纳米级缺陷的成像检测。     

水性胶粘剂，与绿色包装同行

近几年来,随着人们生活水平的提高。食品卫生和安全已经成为公共热点话题,然而人们在崇尚绿色天然食品的同时,却往往忽略了食品复合软包装袋是否安全和卫生。近两年来,新闻媒体报道国内许多地区不断出现食品安全问题,部分正是源自于包装,许多食品生产厂家开始重视其产品包装的残留溶剂超标问题。印刷包装厂家也开始调整思路,着眼于减少印刷和复合中的有机溶剂。在食品包装领域,一场“环保风暴”正在刮起。     

水性胶粘剂，与绿色包装同行

近几年来,随着人们生活水平的提高,食品卫生和安全已经成为公共热点话题,然而人们在崇尚绿色天然食品的同时,却往往忽略了食品复合软包装袋是否安全和卫生。近两年来,新闻媒体报道国内许多地区不断出现食品安全问题,部分正是源自于包装,许多食品生产厂家开始重视其产品包装的残留溶剂超标问题。印刷包装厂家也开始调整思路,着眼于减少印刷和复合中的有机溶剂。在食品包装领域,一场“环保风暴”正在刮起。     

导热胶粘剂研究

导热胶粘剂因良好的导热及力学性能广泛应用于微电子封装以及热界面材料,对于电子元器件散热具有重要意义.介绍了导热胶粘剂导热原理、导热模型,分析了影响导热率的因素,以及提高导热率的途径;综述了导热非绝缘及导热绝缘胶粘剂的研究进展,最后展望了其应用前景.     

Glass-ceramics with random and oriented microstructures

The variation of a number of physical properties of a glass-ceramic composition as a function of the crystallization heat-treatment temperature are reported. The properties studied include mechanical strength, modulus of elasticity, electrical properties and linear coefficient of thermal expansion. It is shown that several of the properties are dependent on microstructural effects. This dependence is especially marked for modulus of rupture and is also apparent for electrical properties such as conductivity and loss tangent. For the latter, however, compositional changes in the residual glass phase also exert a significant influence. For other properties, such as indentation hardness, the microstructural dependence is less well defined.     

Glass-ceramics with random and oriented microstructures

The technique of hot extruding a glass-ceramic to produce a material with an aligned crystal microstructure is described. The results of a statistical investigation to analyse the degree of morphological orientation of an extruded glass-ceramic based on the Li₂O-SiO₂ system are reported. Details are also presented of the determination of the crystallographic orientation in the aligned glass-ceramic.     

Anisotropic imbibition on surfaces patterned with polygonal posts

We present and interpret lattice Boltzmann simulations of thick films spreading on surfaces patterned with polygonal posts. We show that the mechanism of pinning and depinning differs with the direction of advance, and demonstrate that this leads to anisotropic spreading within a certain range of material contact angles.     

Physics of perpendicular recording with a patterned soft underlayer

In this paper, it is argued that perpendicular recording in the most popular current form--with the use of a continuous soft underlayer (SUL)--may not be the most optimal way to maximize the achievable areal density. As a possible solution, patterning of SUL is discussed. The purpose of patterning of a SUL is to effectively move the image head closer to the recording media, as compared to the real recording head, and thus increase the net recording field and the field gradient across the thickness of the media. Various patterning configurations and combinations with recording layers are comparatively studied. It is illustrated that with a patterned SUL, the recording and sensitivity fields, responsible for writing and reading information, respectively, could be not only increased by several factors but also localized across the entire thickness of the recording media.     

Fatigue modeling of materials with complex microstructures

A new approach and method of the analysis of microstructure-lifetime relationships of materials with complex structures is presented. The micromechanical multiscale computational analysis of damage evolution in materials with complex hierarchical microstructures is combined with the phenomenological model of fatigue damage growth. As a result, the fatigue lifetime of materials with complex structures can be determined as a function of the parameters of their structures. As an example, the fatigue lifetimes of wood modeled as a cellular material with multilayered, fiber reinforced walls were determined for different parameters of wood microstructures. In so doing, 3D hierarchical finite element models of softwood, and a computational technique, including the repeating restart and model change procedures, have been employed to model the fatigue response of latewood.     

Liquid-Superrepellent Bioinspired Fibrillar Adhesives

Bioinspired elastomeric fibrillar surfaces have significant potential as reversible dry adhesives, but their adhesion performance is sensitive to the presence of liquids at the contact interface. Like their models in nature, many artificial mimics can effectively repel water, but fail when low-surface-tension liquids are introduced at the contact interface. A bioinspired fibrillar adhesive surface that is liquid-superrepellent even toward ultralow-surface-tension liquids while retaining its adhesive properties is proposed herein. This surface combines the effective adhesion principle of mushroom-shaped fibrillar arrays with liquid repellency based on double re-entrant fibril tip geometry. The adhesion performance of the proposed microfibril structures is retained even when low-surface-tension liquids are added to the contact interface. The extreme liquid repellency enables real-world applications of fibrillar adhesives for surfaces covered with water, oil, and other liquids. Moreover, fully elastomeric liquid-superrepellent surfaces are mechanically not brittle, highly robust against physical contact, and highly deformable and stretchable, which can increase the real-world uses of such antiwetting surfaces.     

Superplastic microstructures

Abstract

The production of fine, stable equiaxed grains, having disordered high angle boundaries, is a prerequisite for superplastic behaviour in crystalline solids. The way that superplastic microstructures can be achieved in pseudo-single-phase and duplex materials by thermomechanical processing is discussed for a number of commercially significant materials. The resulting superplastic deformation characteristics are outlined, as are the factors that influence cavitation during superplastic flow. Alloys based on aluminium, titanium, copper, iron, and nickel are considered, and also aluminium based metal-matrix composites, intermetallic phases, and crystalline ceramic materials. Recent work on markedly enhanced superplastic behaviour in aluminium and copper alloys and in stainless steels is reported, and the similarities between superplasticity in crystalline ceramics and metallic materials is discussed. The development of superplastic microstructures in metal-matrix composites, intermetallic phases, and ceramics has enhanced their formability and their potential as high temperature structural materials.

MST/1298     

High-resolution image reconstruction in fluorescence microscopy with patterned excitation

We discuss data treatment strategies in structured illumination microscopy, using simulated and experimental data. In the setup, the illumination pattern is generated by projecting a movable pinhole mask into the sample, and a wide-field fluorescence microscope image is acquired for each pattern position. The structured illumination data obtained from a two-dimensional illumination pattern can be treated by projection strategies such as in video confocal microscopy (sum, maximum, maximum minus minimum, and superconfocal), by a scaled subtraction of the out-of-focus estimate, or by a modified version of the Fourier-space treatment, as is known for data from one-dimensional structured illumination. We investigate the influence of some data processing strategies on unwanted effects such as residual patterning and local deviations from linearity in the reconstructed intensity.     

Thermal healing of the sub-surface damage layer in sapphire

The sub-surface damage layer formed by mechanical polishing of sapphire is known to reduce the mechanical strength of the processed sapphire and to degrade the performance of sapphire based components. Thermal annealing is one of the methods to eliminate the sub-surface damage layer. This study focuses on the mechanism of thermal healing by studying its effect on surface topography of a- and c-plane surfaces, on the residual stresses in surface layers and on the thickness of the sub-surface damage layer. An atomically flat surface was developed on thermally annealed c-plane surfaces while a faceted roof-top topography was formed on a-plane surfaces. The annealing resulted in an improved crystallographic perfection close to the sample surface as was indicated by a noticeable decrease in X-ray rocking curve peak width. Etching experiments and surface roughness measurements using white light interferometry with sub-nanometer resolution on specimens annealed to different extents indicate that the sub-surface damage layer of the optically polished sapphire is less than 3 μm thick and it is totally healed after thermal treatment at 1450 °C for 72 h.     

Enhanced wet etching of patterned GaN with ion implantation

We present the enhanced wet etching of GaN epilayer implanted with Au+ ion. Patterned GaN with 2 microm-wide sink-like strips was achieved by using 500 keV Au+ ion implantation and KOH etching. The Dependence of etching depth on etching time for the implantation at different ion fluences was investigated. The experiment showed that the damaged GaN area could be almost etched out at high ion fluence, and the etching depth could exceed the project range of incident 500 keV Au+ ion. The etch pits could be observed at the bottom of the etched area. The -400 nm depth etching could be achieved with high fluence implantation after a long etching time, and the edge of etched area could remain clear until the etching process had passed 40 min. As-deposited SiO2 spheres were used to mask the GaN sample in implantation process to investigate the etching effect. -70 nm wave of the GaN surface was observed. The results of our experiments may suggest an approach to the fabricating of GaN devices.