SH Acoustic Waves in a Lithium Niobate Plate and the Effect of Electrical Boundary Conditions on Their Properties

It is theoretically and experimentally confirmed that the electromechanical coupling coefficient of SH waves propagating in a Y-cut lithium niobate plate along the X direction can exceed 30% when the plate thickness satisfies the condition h/λ= 0.02–0.15. This value of the coupling coefficient is approximately six to seven times greater than the maximal value obtained for SAW in the same material. Such a high value of K ² offers a possibility to control the wave velocity by varying the electrical boundary conditions, e.g., by moving a conducting screen toward the plate surface. The effect of such a screen on the properties of the SH waves is studied both theoretically and experimentally. On the whole, the results of the study show that the use of SH waves offers considerable improvements in the parameters of the known SAW devices and also opens up the possibilities for the development of new devices and sensors that have to operate in contact with a liquid medium.     

不同生长条件下ZnO薄膜电学性质的研究

ZnO薄膜中的高的背景电子浓度能够对p型掺杂形成补偿,从而对p型掺杂造成障碍,了解高背景电子浓度的来源有助于对p型掺杂的研究。本文采用分子束外延技术在不同真空度下在a面蓝宝石衬底上生长了一系列氧化锌薄膜,发现在低真空度下生长的样品的载流子浓度较高,为10¹⁹ cm^-3量级;而高真空度下生长的样品,其载流子浓度比低真空生长的样品显著降低,降低了3个数量级。在相同条件下生长的样品,通过不同的后处理手段进行处理后,其电子浓度未发生明显变化,说明氧空位等本征缺陷不是ZnO薄膜中电子的主要来源,高背景电子浓度应该与生长过程中非故意引入的杂质相关。通过低温光致发光表征,发现低真空度下生长的样品在低温下3.366 eV处有强的施主束缚激子发光峰,而高真空度下生长的样品的此发光峰显著变弱。由此,高电子浓度被归结为与生长过程中非故意引入的氢杂质相关。     

沟道宽度对ZnO-TFT电学性能的影响

用射频磁控溅射法生长的ZnO薄膜作为有源层,制备出了ZnO基薄膜晶体管(ZnO-TFT),并在空气环境下350℃退火1 h,研究了沟道宽度对ZnO-TFT器件性能的影响。实验结果表明:阈值电压随着沟道宽度的减小而增加,这是由于沟道越窄,载流子被捕获的几率越大,在相同栅压下沟道内可动载流子浓度越小,相应的阈值电压就越大;饱和迁移率随着沟道宽度的减小而增加,认为这是由源/漏电阻的侧壁效应及边缘电子场效应引起的附加电流所致。     

Micromagnetic and Magnetooptical Properties of Ferromagnetic/Heavy Metal Thin Film Structures

Physics of the Solid State - The magnetic properties of CoPt, CoPd, and FePd thin films with different contents of a ferromagnetic material fabricated by electron beam evaporation have been...     

高择优取向Mo薄膜的直流磁控溅射制备及其电学性能

使用直流磁控溅射法在玻璃基底上沉积Mo薄膜,采用X射线衍射仪、原子力显微镜和四探针测试系统研究了溅射工艺对Mo薄膜的结构、形貌和电学性能的影响.结果表明:当基片温度为150 ℃时,薄膜获得(211)晶面择优取向生长,而在低于250 ℃的其它温度条件下,样品则表现为(110)晶面择优取向生长.进一步的表面形貌分析显示:薄膜的粗糙度随基片温度变化不明显,其值大约为0.35 nm,随溅射功率密度的增大而变大|电学性能方面:随着溅射功率密度的升高,薄膜导电性能迅速增强,电阻率呈现近似指数函数衰减|随着基底温度的升高,薄膜的电阻率先减小后增大,当基底温度为150 ℃时,薄膜电阻率降低至最小值2.02×10-5 Ω·cm.     

矩形微槽蒸发薄液膜新边界条件的设定

采用了一种新的边界条件来求解微槽内蒸发薄液膜的控制方程。这种新的边界条件保证在毛细微槽中,本征弯液面区域的液面弯曲中心位于微槽的中心线上,从而消除了传统微槽薄液膜计算模型中产生的物理矛盾。计算结果显示随着过热度的增加,本征弯液面部分的曲率半径不是恒定的,而是逐渐增加的,这导致了本征区域毛细吸力的降低。计算结果同时表明在本征区域的较薄位置,存在一个狭窄的热流密度相当大的子区域。在数值研究中,如果将此子区域用恒定半径的区域来替代,从理论上来讲是不合理的。     

Calculation of the RF Conductivity and Hall Constant of a Thin Metal Film

The kinetic problem of finding the rf conductivity and Hall constant of a thin metal film placed in a transverse steady magnetic field and a longitudinal variable electric field has been considered. It has been assumed that electrons diffusely reflect from the upper and lower surfaces of the film. No limitations have been imposed on the relationship between the thickness of the film and the electron free path. The dependences of the conductivity and Hall constant on dimensionless parameters, namely, electric field frequency, magnetic field induction, and thickness of the film, have been studied. Calculation results have been compared with the experimental data.     

高择优取向Mo薄膜的直流磁控溅射制备及其电学性能

使用直流磁控溅射法在玻璃基底上沉积Mo薄膜,采用X射线衍射仪、原子力显微镜和四探针测试系统研究了溅射工艺对Mo薄膜的结构、形貌和电学性能的影响.结果表明:当基片温度为150℃时,薄膜获得(211)晶面择优取向生长,而在低于250℃的其它温度条件下,样品则表现为(110)晶面择优取向生长.进一步的表面形貌分析显示:薄膜的...     

衬底温度对氧化锌薄膜电学性质的影响

氧化锌是一种性能良好的半导体材料,可以用作薄膜场发射阴极中的电子传输层材料,主要研究了用磁控溅射方法在不同衬底温度下生长ZnO薄膜的电学特性,分析了ZnO薄膜的电阻率和击穿场强随温度的变化关系。     

Effect of Annealing Conditions on Properties of Sol-Gel Derived Al-Doped ZnO Thin Films

Transparent conductive Al-doped ZnO （AZO） thin films are prepared on normal glass substrates by the sol-gel spin coating method. The effects of drying conditions, annealing temperature and cooling rate on the structural, electrical and optical properties of AZO films are investigated by x-ray diffraction, scanning electron microscopy, the four-point probe method and UV-VIS spectrophotometry, respectively. The deposited films show a hexagonal wurtzite structure and high preferential c-axis orientation. As the drying temperature increases from 100℃ to 300℃ the resistivity of AZO films decreases dramatically. In contrast to the annealed films cooled in a furnace and in air, the resistivity of the annealed film which is cooled at -15℃is greatly reduced. Increasing the cooling rate dramatically increases the electrical conductivity of AZO films.     

ZnO薄膜的制备和发光特性的研究

用射频磁控溅射的方法在石英衬底上沉积了氧化锌薄膜，在室温下测量了样品的XRD曲线、吸收光谱以及光致发光光谱。探讨了气氛中氧气与氩气比对制备薄膜的影响，从XRD谱中可以看出，样品具有较好的结晶状态。另外，样品在紫外有较强的吸收，而其光致发光也是较强的紫外发射，这表明带间跃迁占了主导地位，以上结果说明：用溅射方法制备的ZnO薄膜结晶质量较好，富锌状态有所改善。     

亚酞菁薄膜的光谱和光存储性质研究

利用真空蒸镀法制备了一种新的三硝基溴硼亚酞菁（BTN－SubPc)薄膜。在室温下测试了该亚酞菁染料在溶液和薄膜态的吸收光谱、薄膜态的反射和透过光谱，发现该薄膜在500nm-650nm波长范围内具有优良的吸收和反射特性。在632.8nm光盘静态测试仪上测试了覆盖有金属反射层的BTN－SubPc薄膜的静态光存储性能，结果表明，用较小功率和较窄脉宽的激光辐照膜片时，可获得大于30％的反射率对比度，显示出该材料用作短波长光存储介质（特别是用于可录型数字多用光盘）的巨大潜力。     

金属有机化学气相沉积生长Zn1-xMnxSe薄膜的发光和磁光性质

利用金属有机化学气相沉积(MOCVD)方法在GaAs衬底上生长了不同组分的Zn_1-xMn_xSe薄膜。X射线衍射和X射线摇摆曲线证明样品具有较好的结晶质量。在低温、强磁场下对样品的发光进行了研究,在带边附近观察到两个发光峰的相对强度随着磁场增强发生了变化。通过变温光谱探讨了这两个发光峰的来源,并被分别归因于自由激子跃迁和与Mn有关的束缚态激子跃迁。同时随着磁场的增强,ZnMnSe带隙发光红移是由于类S带和类P带电子与Mn离子的3d⁵电子的自旋交换作用。     

蓝光ZnO薄膜的特性研究

采用反应溅射法在n型硅（100）衬底上制备了ZnO薄膜,分别用X射线衍射仪、原子力显微镜和荧光分光光度计对样品的结构、表面形貌和光致发光特性进行了表征。X射线衍射结果表明,实验中制备出了应变小的c轴择优取向的ZnO薄膜;原子力显微镜观察表明,薄膜表面平整,颗粒大小约为50nm,为柱状结构,颗粒垂直于硅衬底表面生长;在室温光致发光（PL）谱中观察到了波长位于434nm处的较窄的强蓝光发射峰,该蓝光峰的半峰全宽约为50meV。对蓝光峰的发光机制进行了讨论,并推断出该蓝光峰来源于电子从Zn填隙缺陷能级向价带顶跃迁。     

Influence of Small-Size Contaminations on Thin Film Structural Properties

An approach for studying the influence of nano-particles on the structural properties of deposited thin films is proposed. It is based on the molecular dynamic modeling of the deposition process in the presence of contaminating nano-particles. The nano-particle is assumed to be immobile and its interaction with film atoms is described by a spherically symmetric potential. The approach is applied to the investigation of properties of silicon dioxide films. Visualization tools are used to investigate the porosity associated with nano-particles. The structure of the film near the nano-particle is studied using the radial distribution function. It is found that fluctuations of film density near the nano-particles are essentially different in the cases of low-energy and high-energy deposition processes.     

Magnetic Properties of Permalloy Thin Film Edges

Russian Physics Journal - The paper presents the results of ferromagnetic resonance (FMR) spectrometry of magnetic properties of nanocrystalline thin films obtained by magnetron sputtering of...     

氧分压对PLD制备ZnO薄膜结构和发光性质的影响

采用脉冲激光沉积(PLD)技术,在Si(100)衬底上制备出高度c轴取向的ZnO薄膜。通过X射线衍射(XRD)谱,扫描电镜(SEM)和室温光致发光(PL)光谱的测量,研究了生长气氛压强的改变对薄膜结构和光致发光的影响。实验结果表明,当氧压从10Pa升高到100Pa时ZnO(002)衍射峰的半峰全宽(FWHM)增大。可以认为这是由于较高的氧压下,到达衬底表面的离子动能减小。这样部分离子没有足够的能量迁移到生长较快的(002)面,c轴取向变差,导致(002)衍射峰的强度降低,半峰全宽增大。随着氧压增大,紫外发光强度增强。这可能是氧压变大,薄膜的化学配比升高,说明化学配比对UV发光的影响要大于薄膜微结构的影响。改变氧气压强对薄膜的表面形貌也有较大的影响。     

X-Ray Radiation Sensing Properties of ZnS Thin Film:A Study on the Effect of Annealing

Chemically synthesized ZnS thin film is found to be a good x-ray radiation sensor. We report the effect of annealing on the x-ray radiation detection sensitivity of a ZnS thin film synthesized by a chemical bath deposition technique.The chemically synthesized ZnS films are annealed at 333, 363 and 393 K for 1 h. Structural analyses show that the lattice defects in the films decrease with annealing. Further, the band gap is also found to decrease from3.38 to 3.21 eV after annealing at 393 K. Current-voltage characteristics of the films are studied under dark and x-ray irradiation conditions. Due to the decrease of lattice defects and band gap, the conductivity under dark conditions is found to increase from 2.06×10~(-6)to 1.69×10~(-5) S/cm, while that under x-ray irradiation increases from 4.13×10~(-5) to 5.28×10~(-5)S/cm. On the other hand, the x-ray radiation detection sensitivity of the films is found to decrease with annealing. This decrease of detection sensitivity is attributed to the decrease of the band gap as well as some structural and surface morphological changes occurring after annealing.