弹性表面波用LiTaO3晶体的生长

x-切112°y方向的LiT_2O_3晶体具有优良的SAW性能,特别适用于制作TV-PTF滤波器,是目前最好的基片材料之一.为了提供优质而经济的基片材料,用铂铑坩埚在N_2气氛中成功地生长了直径40—45mm,长度50—60mm的LiTaO_3晶体.D/D≈0.6,得料率达50％以上.本文对大直径LiTaO_3晶体生长的热场及工艺条件进行了探讨,并测试了所生长晶体的压电、介电、弹性常数和表面波性能.     

通讯波段禁带胶体光子晶体的制备及实验参数研究

采用直径为700nm的二氧化硅微球,通过垂直沉积法在玻璃基片上制备了位于光通讯波段的禁带胶体光子晶体。研究了不同蒸发温度、湿度条件、干燥过程对样品晶体质量的影响。用扫描电子显微镜(SEM)对其形貌进行了观测。实验结果表明,在温度为65℃,相对湿度为70%,缓慢干燥条件下制备出的样品具有较好的晶体质量,晶体在大范围内保持了面心立方(FCC)单晶结构,其(111)面平行于生长基片。     

钆镓石榴石单晶中的缺陷

一、引 言 做磁泡材料基片用的钆镓石榴石单晶(即Gd3Ga5O12,简写为GGG),要求有很高的完整性.GGG晶体中的缺陷,特别是露在晶片表面的缺陷,会影响外延磁性膜的质量.在外延膜中形成钉扎,阻碍磁泡运动.GGG晶体中发现的主要缺陷有包裹物、核心、生长条纹和位错.为了得到完整性好的晶体,观察和研究这些缺陷。找出消除这些缺陷的规律,就显得十分必要了. 二、实验方法 在需要检查的晶体部位。切取1.8—2.0mm厚的薄片,经研磨、抛光和超声清洗三道工序后,样品厚度约为1.2mm.这种抛光的片子就可在偏光显微镜下观察包裹物和核心两种缺陷.若要观察位…     

PbWO_4晶体的光输出与能量分辨研究

研究了多种包装材料和包装工艺对钨酸铅(PbWO4)晶体光输出和能量分辨的影响,测量结果与基于GEANT4的模拟结果符合很好,并由此确定了晶体的最佳包装方法。     

二维平板光子晶体直波导的制备和光传输特性的测量

利用聚焦离子束刻蚀的方法在SOI(silicon on insulator)基片上制备了W3型二维光子晶体直波导.观察并测量了近红外激光通过光子晶体波导的散射图形和透过谱.实验结果说明，激光在有引入引出脊形波导的光子晶体直波导中具有很好的传输特性. 关键词： 光子晶体波导 光子带隙 脊型波导     

感应耦合等离子体增强射频磁控溅射沉积ZrN薄膜及其性能研究

利用感应耦合等离子体(ICP)增强射频磁控溅射技术在Si(111)片和M2钢表面制备了ZrN薄膜,研究了基片的温度和ICP功率对ZrN薄膜的结构以及性能影响.研究发现：在基片温度≤300℃沉积的ZrN薄膜择优取向为(111);基片温度达到450℃时薄膜出现ZrN(200)衍射峰,ZrN(111)晶面的织构系数明显降低.传统磁控溅射沉积薄膜为柱状结构,当ICP为200 W,基片温度为300℃时沉积薄膜中柱状晶体消失;随着基片温度的升高,N/Zr元素比例降低,并且薄膜的电阻率下降;相对于传统溅射,ICP增强射 关键词： 感应耦合等离子体 磁控溅射 ZrN 微结构     

对流自组装2维胶体晶体成膜趋势和覆盖率

从自组装理论出发, 分析对流自组装2维胶体晶体中空白、条纹区域出现的机理,并在实验上予以验证。通过研究得知, 2维胶体晶体的自组装过程呈现空白、条纹、大面积单层、双层条纹的趋势。从胶体晶体覆盖率的角度出发研究2维胶体晶体的组装参数与质量之间的关系,结果表明:胶体晶体的总覆盖率与基片提拉速度倒数呈线性正比,和粒子体积分数呈反比例函数关系; 受到多种因素的影响,大面积2维胶体晶体总是伴随着一定比例的空白区域和双层区域出现,提拉法所能获得的最大单层覆盖率为95%。     

锗酸铋(BGO)长时延声表面波卷积器

BGO长时延声表面波卷积器是在国际上首创,它是用慢声速压电晶体锗酸铋(Bi_(12)Geo_(20))作基片,构成具有特别长的相互作用时间的卷积器。在解决了相关的理论、设计、大面积平面光刻工艺及外电路匹配等问     

基片温度对SiNx薄膜结晶状态及机械性能的影响

利用微波电子回旋共振增强磁控反应溅射法在不同基片温度下制备无氢SiN_x薄膜.通过傅里叶变换红外光谱、透射电子显微镜、台阶仪、纳米硬度仪等表征技术,研究了基片温度对SiN_x薄膜结晶状态、晶粒尺寸、晶体取向等结晶性能以及薄膜的生长速率、硬度等机械性能的影响,并探讨了薄膜结晶性能与机械性能之间的关系.研究结果表明,在基片温度低于300℃时制备的SiN_x薄膜以非晶状态存在,硬度值仅为18GPa左右;基片温度 关键词： x')" href="#">SiN_x 磁控溅射 微观结构 硬度     

FCC结构胶体光子晶体的制备及其带隙特性测量

基于对光纤传输特性和胶体光子晶体制备方法的研究,提出了用外加电场控制的方法制备光子带隙位于通讯波段的FCC结构的胶体光子晶体,并用光纤系统测试胶体光子晶体的带隙特性.采用RSOFT模拟了胶体光子晶体的带隙,分析了带隙位于通讯波段时所需的胶体微球的基本参量(微球折射率和直径).采用自组装的方法,用步进电机控制玻璃基片向上的拉升速率.速率为5 μm/s,同时外加一电场.用扫描电镜观测胶体晶体的表面形貌,并设计了单模光纤系统测量胶体光子晶体的带隙特性.测试的透射谱线表明胶体光子晶体的带隙中心波长为1552 nm.测试结果和模拟结果具有很好的一致性,误差只有2 nm.     

Theory of the epitaxial crystallization of polymers: IV. Chain packing energetics of the initially deposited monolayer — application to the PENaCI system

The packing/surface energetics for the initial layer of epitaxially deposited polyethylene on NaCl has been calculated as a function of the total interactive geometry. Three stable packing modes are found. One mode corresponds to the high energy monoclinic packing observed experimentally. The other two forms are not readily identified with any known crystal packing modes although minor geometric alternations in both forms would lead to the familiar orthorhombic packing of polyethylene chains. The computations indicate that the substrate forces induce a strain within the monolayer of chains that results in specific positioning of PE chains over Na⁺ rows.     

石英衬底上GaN薄膜沉积及其光学性能的研究

GaN薄膜材料广泛应用于发光二极管(LED),激光二极管(LD)等光电器件。但是GaN基器件的制备与应用以及器件推广很大一部分取决于其器件的价格,常用的方式是在单晶蓝宝石衬底上沉积制备GaN薄膜样品,单晶蓝宝石衬底晶向择优,可以制备出高质量的GaN薄膜样品,但是单晶蓝宝石衬底价格昂贵,一定程度上限制了其GaN基器件推广使用。如何在廉价衬底上直接沉积高质量的GaN薄膜,满足器件的要求成为研究热点。石英玻璃价格廉价,但是属于非晶体,没有择优晶向取向,很难制备出高质量薄膜样品。本研究采用等离子体增强金属有机物化学气相沉积系统在非晶普通石英衬底上改变氮气反应源流量低温制备GaN薄膜材料。制备之后采用反射高能电子衍射谱、X射线衍射光谱、室温透射光谱和光致光谱对制备的薄膜进行系统的测试分析。其结果表明：在氮气流量适当的沉积参数条件下,所制备的薄膜具有高C轴的择优取向,良好的结晶质量以及优异的光学性能。     

Photoluminescence Efficiency of Substituted Quaterthiophene Crystals

The photoluminescence (PL) efficiency of substituted alpha-conjugated quaterthiophene crystals shows marked differences depending on crystal packing and molecular geometry. This effect is studied by evaluating the role of the intermolecular interactions and the effects of the single molecule conformation on the intersystem crossing (ISC) rate. The comparison of these calculations with absolute quantum efficiency measurements and with the experimental temperature dependence of the PL decay time, indicates that the differences in PL efficiency are not inherent to crystal packing effects but they are determined by the ISC rate.     

Crystallographic contribution to the formation of the columnar grain structure in cobalt films deposited at oblique incidence

The geometric and crystallographic structures for cobalt films deposited at 75° and 45° by sputtering were investigated on the basis of optical and magnetic measurements and X-ray analysis. The substrate temperature was 332 K and the film thickness ranged from 20 to 900 nm. The alignments of columnar grains below and above 50 nm are perpendicular and parallel to the incidence plane, respectively, and the packing density of columnar grains constituting the parallel alignment decreases with increasing thickness at both incidence angles. At the high incidence angle of 75° the parallel alignment is more well-defined and its packing density is lower. The conclusions from these results are as follows. (1) Above 50 nm the crystal habit induces the two-degree orientation of the HCP phase through the geometric selection. Higher incidence angle enhances the geometric selection. (2) The crystal size necessary to exhibit the crystal habit is independent of the incidence angle.     

聚甲基丙烯酸肉桂酰氧基乙酯的光化学反应在液晶分子排列取向中的作用

研究了光聚合物材料聚甲基丙烯酸肉桂酰氧基乙酯(CEMC)对液晶材料LC-6710A的取向作用,取向层表面在光化学反应前后的变化;测量了光控取向膜液晶盒中液晶分子的预倾角及单面光控取向扭曲向列液晶显示器(TNLCD)的电光特性和时间响应特性,研究了这种材料的光化学反应过程,以及液晶分子排列取向的机理.     

TiO2和SiO2薄膜应力的产生机理及实验探索

对最常用的TiO₂和SiO₂薄膜应力, 包括应力模型、应力测试方法和不同实验条件下的应力测试结果作了研究.基于曲率法模型，对TiO₂和SiO₂单层膜和多层膜进行了实验测试，得到了一些有价值的结果，特别是离子辅助淀积和基板温度等工艺参数对薄膜应力的影响.提出了薄膜聚集密度是应力的重要因素，低聚集密度产生张应力，而高聚集密度产生压应力.在多层膜中通过调节工艺参数，适当地控制张应力或压应力，可使累积应力趋向于零. 关键词： 薄膜应力 离子辅助淀积 聚集密度     

液晶显示用取向材料聚甲基丙烯酸肉桂酰氧基乙酯的光控取向研究

通过实验研究了光聚合物材料聚甲基丙烯酸肉桂酰氧基乙酯（ＣＥＭＣ）的光化学反应过程, 以及对液晶材料ＬＣ－６７１０Ａ 的取向能力． 通过原子力显微镜（ＡＦＭ）观察了取向层表面在光化学反应前后的变化, 测量了光控取向膜液晶盒中液晶分子的预倾角及单面光控取向扭曲向列液晶显示器（ＴＮＬＣＤ）的电光特性和时间响应特性曲线, 研究了液晶分子排列取向的机理．     

V-doped MgAl6O10:novel luminescence substrate for phosphor-free UV-white LEDs

V-doped MgAl6O10 is grown by the conventional Czochralski method. The crystal structure and the cell parameters are analyzed through X-ray diffraction experiments. The absorption and emission spectra are investigated. Under pumping at 324 nm, the emission spectra of V-doped MgAl6O10 obtain two emission peaks at the wavelengths of 471 and 570 nm. Two emission bands of the spectra combine to produce a spectrum that is perceived as white by the naked eye. Therefore, V-doped MgAl6O10 single crystal can be applied as substrate for phosphor-free ultraviolet (UV)-white light-emitting diodes (LEDs).     

Optical constants of DUV/UV fluoride thin films

High-refractive-index materials LaF3, NdF3, and GdF3 and low-refractive-index materials MgF2, A1F3, and Na3A1F6 single thin films are deposited by a resistive-heating boat at different depositing rates and specific substrate temperatures on single crystal MgF2 substrates. Transmittances of all fluoride thin films are measured using commercial spectrometer in the ambient atmosphere and under vacuum using synchrotron radiation instrument in the wavelength region from 190 to 500 am. The optical constants of these materials are determined by envelope method and iterative algorithm on the basis of transmittance measurements.     

Calibration in Auger electron spectroscopy by means of coadsorption

The combined adsorption of two elements on a single crystal substrate can be readily examined by LEED and AES. By careful monitoring of the AES signals during adsorption it is possible to detect the formation of a complete, binary, monolayer. The method requires that the second absorbate (typically, an easily deposited metal) forms first on the uncovered substrate and then on top of the first adsorbate by a layer-by-layer growth mechanism. By obtaining binary monolayers in different compositions the spectrometer may be calibrated for both adsorbates. The basis of the method and its application to sulphur and oxygen on copper are described.