硅基高度择优取向PZT厚膜的制备及性能研究

应用溶胶-凝胶法成功地在以SrTiO3(STO)为模板/阻挡层Si(001)基片上制备了La-Sr-Co-O/ Pb(Zr0.5Ti0.5)O3(PZT)/La-Sr-Co-O/STO/Si异质结,PZT的厚度为0.8μm.研究了异质结的结构和性能.实验发现,PZT结晶良好、具有(001)高度择优取向以及较高的极化强度和较小的极化强度对脉冲宽度的依赖性;当外加电压为50V时,电阻率仍＞108Ω·cm.     

硅基平面波导材料的制作

采用火争水解法（ＦＨＤ）在Ｓｉ基上淀ＳｉＯ２预制材料,然后在真空中／空气气氛中高温处理（１３８０℃）,制得玻璃化的ＳｉＯ２膜材料;该材料膜厚适中（１０－３０μｍ）、平整度好、光滑透明,适合制作单模、多模列阵平面波导光栅。并利用ＸＲＤ、ＳＥＭ、台阶仪等仪器对ＳｉＯ２膜进行了测试分析。     

Fabrication of nano-sized metal patterns on flexible polyethylene-terephthalate substrate using bi-layer nanoimprint lithography

Polymer films are widely used as a substrate for displays and for solar cells since they are cheap, transparent and flexible, and their material properties are easy to design. Polyethylene-terephthalate (PET) is especially useful for various applications requiring transparency, flexibility and good thermal and chemical resistance.In this study, nano-sized metal patterns were fabricated on flexible PET film by using nanoimprint lithography (NIL). Water-soluble poly-vinyl alcohol (PVA) resin was used as a planarization and sacrificial layer for the lift-off process, as it does not damage the PET films and can easily be etched off by using oxygen plasma. NIL was used to fabricate the nano-sized patterns on the non-planar or flexible substrate. Finally, a nano-sized metal pattern was successfully formed by depositing the metal layer over the imprinted resist patterns and applying the lift-off process, which is economic and environmentally friendly, to the PET films.     

Algebraic grid generation on trimmed parametric surface using non‐self‐overlapping planar Coons patch

Using a Coons patch mapping to generate a structured grid in the parametric region of a trimmed surface can avoid the singularity of elliptic PDE methods when only C¹ continuous boundary is given; the error of converting generic parametric C¹ boundary curves into a specified representation form is also avoided. However, overlap may happen on some portions of the algebraically generated grid when a linear or naïve cubic blending function is used in the mapping; this severely limits its usage in most of engineering and scientific applications where a grid system of non‐self‐overlapping is strictly required. To solve the problem, non‐trivial blending functions in a Coons patch mapping should be determined adaptively by the given boundary so that self‐overlapping can be averted. We address the adaptive determination problem by a functional optimization method. The governing equation of the optimization is derived by adding a virtual dimension in the parametric space of the given trimmed surface. Both one‐ and two‐parameter blending functions are studied. To resolve the difficulty of guessing good initial blending functions for the conjugate gradient method used, a progressive optimization algorithm is then proposed which has been shown to be very effective in a variety of practical examples. Also, an extension is added to the objective function to control the element shape. Finally, experiment results are shown to illustrate the usefulness and effectiveness of the presented method. Copyright © 2004 John Wiley & Sons, Ltd.     

Fabrication of CIGS solar cells with a Na-doped Molayer on a Na-free substrate

The photovoltaic properties of CIGS cells on an alumina substrate were improved through the use of Na-doped Mo as the bottom layer of a Mo back contact. Na was supplied to the CIGS bulk region from an alumina/Na-doped Mo/Mo structure, similar to the Na diffusion from soda-lime glass. The diffusion of Na from the Na-doped Mo was controlled effectively compared to that from Soda-lime glass (SLG). The present results indicate that Na-doped Mo acts as a Na source material and that the Na amount can be controlled by adjustment of thickness of Na-doped Mo layer, without the use of an alkali barrier layer. The highest conversion efficiency of 13.34% (J_sc = 34.62 mA/cm², V_oc = 0.58 V and FF = 66%) for an active area of 0.45 cm² on an alumina substrate was obtained for 100 nm Na-doped Mo/1000 nm Mo.     

喷雾热解法在硅衬底上生长定向碳纳米管阵列(英文)

以向日葵油的甲基酯为碳源,二茂铁为催化剂前驱体,Ar为载气,通过喷雾热解法在硅衬底上合成定向碳纳米管阵列。结果表明,在硅衬底上原位形成Fe催化剂纳米颗粒。由拉曼光谱、透射电镜图和X-射线衍射谱图显示所制定向碳纳米管阵列具有较好的石墨化程度,其直径为1 0～3 0 nm,管壁约为1 0 nm。所制定向碳纳米管阵列中残留的催化剂含量可以忽略。     

基于低温直接键合的血细胞计数芯片结构制备

研究了一种新颖的微流管道血细胞计数器的结构及其工作原理,采用流体动力学对其液体分层流动特性进行了仿真分析,结合图形制备和低温直接键合工艺制作了硅基微流体管道血细胞计数器结构,并采用红外透射方法对微流体管道结构进行了检测.对封闭管道的流通性及结构的键合强度也进行了测量.研究分析表明,采用上述工艺制备的微流体芯片结构与电子器件兼容性好,具有良好的化学惰性和热稳定性,而且管道结构规则,精度高,键合界面层薄,具有较好的应用前景.     

Fabrication of high frequency ZnO thin film SAW devices on silicon substrate with a diamond-like carbon buffer layer using RF magnetron sputtering

Diamond-like carbon (DLC) film is a promising candidate for surface acoustic wave (SAW) device applications because of its higher acoustic velocity. A zinc oxide (ZnO) thin film has been deposited on DLC film/Si substrate by RF magnetron sputtering; the optimized parameters for the ZnO sputtering are RF power density of 0.55 W/cm², substrate temperature of 380 °C, gas flow ratio (Ar/O₂) of 5/1 and total sputter pressure of 1.33 Pa. The results showed that when the thickness of the ZnO thin films was decreased, the phase velocity of the SAW devices increased significantly.     

Simulation of epitaxial growth on convex substrate using phase field crystal method

Phase field crystal （PFC） model is employed to simulate the process of growth of epitaxial layer on plane-convex substrate with a lattice mismatch and a small inclination angle. The variation of the systematic free energy, the total atomic number of the epitaxial layer, and the effect of the curvature and the angle of the substrate are analyzed. The results show that when the surface of the substrate is plane, the free energy increases with the increase of the substrate inclination angle, and also the total atomic number of the epitaxial layer increases; while the surface of the substrate is convex, the free energy decreases with the increase of substrate angle and so also the total atomic number of the epitaxial layer decrease. This is the reason that the frontier of surface of epitaxial layer changes from the step bunching to the hill-and-valley facet structure with the increasing of the inclination angle of convex substrate. These results are in good agreement with the other method results.     

Fabrication of polycrystalline silicon thin films on glass substrates using fiber laser crystallization

Laser crystallization of amorphous silicon (a-Si), using a fiber laser of λ = 1064 nm wavelength, was investigated. a-Si films with 50 nm thickness deposited on glass were prepared by a plasma enhanced chemical vapor deposition. The infrared fundamental wave (λ = 1064 nm) is not absorbed by amorphous silicon (a-Si) films. Thus, different types of capping layers (a-CeO_x, a-SiN_x, and a-SiO_x) with a desired refractive index, n and thickness, d were deposited on the a-Si surface. Crystallization was a function of laser energy density, and was performed using a fiber laser. The structural properties of the crystallized films were measured via Raman spectra, a scanning electron microscope (SEM), and an atomic force microscope (AFM). The relationship between film transmittance and crystallinity was discussed. As the laser energy density increased from 10-40 W, crystallinity increased from 0-90%. However, the higher laser density adversely affected surface roughness and uniformity of the grain size. We found that favorable crystallization and uniformity could be accomplished at the lower energy density of 30 W with a-SiO_x as the capping layer.     

Thermal conductivity of InAs quantum dot stacks using AlAs strain compensating layers on InP substrate

The growth and thermal conductivity of InAs quantum dot (QD) stacks embedded in GaInAs matrix with AlAs compensating layers deposited on (1 1 3)B InP substrate are presented. The effect of the strain compensating AlAs layer is demonstrated through Atomic Force Microscopy (AFM) and X-ray diffraction structural analysis. The thermal conductivity (2.7 W/m K at 300 K) measured by the 3ω method reveals to be clearly reduced in comparison with a bulk InGaAs layer (5 W/m K). In addition, the thermal conductivity measurements of S doped InP substrates and the SiN insulating layer used in the 3ω method in the 20–200 °C range are also presented. An empirical law is proposed for the S doped InP substrate, which slightly differs from previously presented results.     

微波无损检测热障涂层下金属表面裂缝的参数优化

基于微波在介电材料中的传播理论及其对金属界面特性的敏感性, 利用CST-微波工作室(computer simulation technology-microwave studio)对微波检测热障涂层下金属的裂缝进行了仿真计算, 研究了热障涂层的厚度、 裂缝方向对检测结果的影响, 仿真计算了热障涂层厚度为400 μm、 裂缝长边方向平行于矩形波导探头长边的不同宽度的裂缝。结果表明: 热障涂层厚度不同时, 微波检测金属表面裂缝的敏感工作频率不同; 裂缝方向与波导口长边的夹角为50°～55°时检测敏感度低。裂缝宽度小于8 μm时用本研究中的频率范围无法检测, 裂缝宽度在10～30 μm时检测效果不明显, 裂缝宽度在30 μm～1 mm范围内, 裂缝越宽微波的反射系数相位差越大。因此, 在合适的工作频率下能利用微波无损检测技术对热障涂层下金属表面的裂缝进行无损检测。     

微波无损检测热障涂层下金属表面裂缝的参数优化

基于微波在介电材料中的传播理论及其对金属界面特性的敏感性,利用CST-微波工作室(computer simulation technology-microwave studio)对微波检测热障涂层下金属的裂缝进行了仿真计算,研究了热障涂层的厚度、裂缝方向对检测结果的影响,仿真计算了热障涂层厚度为400 μm、裂缝长边方向平行于矩形波导探头长边的不同宽度的裂缝.结果表明:热障涂层厚度不同时,微波检测金属表面裂缝的敏感工作频率不同;裂缝方向与波导口长边的夹角为50°～55°时检测敏感度低.裂缝宽度小于8 μm时用本研究中的频率范围无法检测,裂缝宽度在10～～30 μm时检测效果不明显,裂缝宽度在30 μm～1 mm范围内,裂缝越宽微波的反射系数相位差越大.因此,在合适的工作频率下能利用微波无损检测技术对热障涂层下金属表面的裂缝进行无损检测.     

Electrochemical fabrication of cadmium telluride quantum dots using porous anodized aluminum on a silicon substrate

A uniform array of uniformly sized cadmium telluride quantum dots is fabricated in this work. A practical multilayer template, composed of a silicon substrate, several metal layers and porous anodized aluminum is used as a mold to electrochemically grow II-VI semiconductor quantum wires. Only standard silicon processing and in situ electrochemical techniques are used to fabricate the template and quantum dots without the need for thin film handling procedures. Fabrication procedures are described and structural characterization using scanning electron microscopy and optical characterization using luminescence are performed. The extension of this technique to the fabrication of quantum wires and quantum wire heterostructures and superlattices, is discussed.     

石墨衬底上具有（220）/（400）择优取向多晶硅薄膜的制备及性质

在石墨衬底上分别制备了具有(220)和(400)择优取向的多晶硅薄膜.首先利用磁控溅射技术直接在石墨衬底上制备非晶硅薄膜层,以及先制备 ZnO 过渡层,再在 ZnO 过渡层上制备非晶硅薄膜层;然后采用快速退火法对非晶硅薄膜晶化,使其形成多晶硅薄膜籽晶层.XRD 测试表明,未引入 ZnO 过渡层的多晶硅薄膜籽晶层具有高度(220)择优取向,而引入 ZnO 过渡层的多晶硅薄膜籽晶层具有高度(400)择优取向;最后在多晶硅籽晶层上通过对流辅助化学气相沉积(CoCVD)制备多晶硅薄膜.根据 SEM、XRD、拉曼测试表明,多晶硅薄膜的性质延续了多晶硅籽晶层的性质,未引入 ZnO 过渡层的样品,具有高度(220)择优取向.引入 ZnO 过渡层后的样品,具有高度(400)择优取向,(400)择优取向的转变有利于后续多晶硅薄膜太阳电池的制作.同时对 Si(220)和 Si (400)择优取向的形成原因做了初步分析.     

Fabrication and mechanism study of CuO layers on double surfaces of polyimide substrate using surface modification

Formation process and mechanism of continuous CuO layers on double surfaces of polyimide films were studied. The composite films were prepared using the facile surface modification and ion exchange technique. By alkaline-induced chemical modification and ion-exchange reaction, Cu²⁺ ions were incorporated into the surface of polyimide substrate. Thermal treatment in ambient atmosphere resulted in the formation of CuO particles that further agglomerated on the film surface and produced well-defined CuO thin layers on the double surfaces of polyimide films. The changes in the chemical structure, surface morphology, crystalline state and the surface roughness with the increase of ambient temperature were investigated. It was interesting to find that the conversion of metallic copper and low valence sub-oxide Cu₂O to high valence oxide CuO was observed in the thermal treatment process. The agglomeration mechanism for the CuO particles was proposed and proved by three steps, which illustrated that copper-catalyzed and oxygen-assisted decomposition of the polyimide overlayer resulted in the agglomeration of CuO particles. The final composite films retained the thermal stability of the pure polyimide.     

Influences of argon plasma cleaning on the die-shear force of chip and copper/polyimide flexible substrate assembly using a non-conductive film

Abstract

A non-conductive film (NCF) and a thermal compression process were combined to assemble a chip onto a flexible substrate. To achieve direct bonding and to enhance the adhesion of a chip on the flexible substrate with NCF, argon plasma was used to clean copper electrodes over a flexible substrate. For flexible substrates which received argon plasma cleaning, low contact angles were obtained, and gold bumps directly contacted copper electrodes to form active input/output (I/O) paths, indicating the contaminants on the flexible substrate were removed and a clean bonding surface could be achieved. Neither delamination nor porosity was observed at the bonding interface between the NCF and copper electrodes. A sound bonding interface with satisfactory die-shear force was achieved. The argon plasma cleaning led to a significant improvement of the die-shear force of a chip bonded onto the flexible substrate using NCF.     

Probe microanalysis investigation and electroreflectance spectroscopy of Hg1−xCdxTe PLD films on silicon patterned substrates

Hg_1−xCd_xTe films were prepared on Si-patterned substrates by the pulse laser deposition technique from a Hg_1−xCd_xTe target (x≈0.2). The effects of different substrate temperatures, ranging from 293 to 543 K, different laser shots number in the range of 10–380, and the morphological type of the patterned substrate on the x-composition of films were studied by electron probe microanalysis (EPMA) and electroreflectance (ER) spectroscopy. The correlation between a film composition measured by EPMA and one determined from ER spectra data was observed.