ZnO/α-Al_2O_3界面结构的掠入射X射线衍射研究

采用脉冲激光沉积(PLD)技术,以α-Al2O3(001)为衬底,在不同衬底温度下制备ZnO薄膜.利用X射线衍射(XRD)和同步辐射掠入射x射线衍射(GID)研究了薄膜的结晶性能和薄膜与衬底的界面结构.实验结果表明,在衬底温度较低(450℃)时,ZnO薄膜主要受衬底拉应力的作用,使界面处a方向的晶格常数增大;而在衬底温度较高(750℃)时,ZnO薄膜主要受衬底压应力的作用,使界面处a方向的晶格常数减小;在优化的衬底温度(650℃)下,ZnO薄膜受到的衬底应力较小,结晶性最好.且ZnO薄膜垂直方向的晶格排列要比面内的晶格排列更有序.     

YBa2Cu3O7—x／La2／3Ca1／3MnO3异质结构薄膜的微结构

本通过高分辨X射线衍射及掠入射(GID)的实验方法对生长在SrTiO3衬底上的LLa2/3Ca1/3MnO3和YBaCu3O7单层膜及YBa2Cu3O7-x/La2／3Ca1／3MnO3异质结构双层薄膜的微结构进行了研究。结果发现,所有薄膜都呈c向生长。由于热膨胀系数的不同而引起的热应力使得LCMO膜的晶格参数与靶材的相差较大。La2/3Ca1/3MnO3在单层腹及双层膜中都由靶材的立方结构变成了薄膜状态的四方结构。YBa2Cu3O7在单层膜及双层膜中都由靶材的正交结构变成了薄膜状态的四方结构。La2/3Ca1/3MnO3膜与YBa2Cu3O7膜在不同的样品中处于不同的应力状态。     

SiGe/Si(100)外延薄膜材料的应变表征研究

如何表征SiGe／Si异质外延薄膜中的应变对提升SiGe器件的性能至关重要。本文详细介绍了卢瑟福背散射／沟道效应(RBS／C)、高分辨率X射线衍射(HRXRD)和拉曼(Raman)谱等技术表征SiGe薄膜中应变的原理。通过这些实验技术,研究了SiGe／Si外延薄膜在氧气和惰性气体氛围下高温退火前后应变弛豫及离子注入Si衬底上外延生长的SiGe薄膜应变状态。     

多层介质/金属紫外滤光膜系的辐照损伤特性

利用电子束蒸发方法制备用于BaF₂晶体慢成分滤光的多层介质/金属紫外滤光膜系。在γ射线、中子和激光辐照环境中研究薄膜的损伤特性。结果表明：薄膜对γ射线和中子具有优良的耐辐照特性；在激光辐照环境中，薄膜的激光损伤阈值受多层薄膜中金属层的影响，激光入射时，最先辐照到的金属层的厚度决定了多层薄膜的耐激光辐照损伤特性。     

原位光电子能谱研究La_2O_3/LaAlO_3/Si电子结构

在超高真空条件下,通过脉冲激光技术沉积La_2O_3/LaAlO_3/Si多层膜结构,原位条件下利用同步辐射光电子能谱研究了LaAlO_3作为势垒层的La_2O_3与Si的界面电子结构。实验结果显示,LaAlO_3中Al的2p峰在沉积和退火前后没有变化;衬底硅的芯能级峰在沉积LaAlO_3时没有变化,但在沉积La_2O_3薄膜和退火过程中,硅峰变弱;O的1S芯能级的峰由多种不用的氧化物薄膜层和反应物中的氧杂化而成。结果表明:LaAlO_3从沉积到退火当中,不参与任何反应,Si与LaAlO_3界面相当稳定;在体系中,阻挡层LaAlO_3起到阻挡硅扩散的作用,进一步表明La_2O_3与硅的界面不太稳定。     

离子束辅助沉积制备TiN/Si3N4纳米超硬膜的工艺研究

采用离子束辅助沉积法(Ion beam assisted deposition,IBAD)在单晶硅片上进行沉积制备了TiN/Si3N4纳米复合超硬薄膜;研究了辅助束流、轰击能量和Ti:Si靶面积比等工艺参数对TiN/Si3N4超硬纳米复合薄膜性能的影响.此外采用纳米硬度计、光电子能谱(X-ray photoelectron spectrum,XPS)和x射线衍射分析(X-raydiffraction,XRD)方法研究了纳米复合薄膜的性能、成分与组织结构;采用原子力显微镜(Atomic forcemicroscopy,AFM)分析了薄膜的表面形貌,并初步探讨了TiN/Si3N4纳米复合超硬薄膜的生长机理.     

La0.7Ca0.3MnO3薄膜的掠入射X射线衍射研究

利用90°离轴射频磁控溅射方法将Lao.7Ca0.3MnO3(LCMO)沉积于(001)取向的SrTiO3(STO)、MgO和α-Al2O3(ALO)单晶基片上,薄膜厚度均为500 A.通过掠入射X射线衍射技术测量了LCMO薄膜的横向晶格常数(即面内晶格常数),结合常规X射线衍射研究了LCMO薄膜的晶格应变及其弛豫情况.结果表明,LCMO薄膜在MgO和ALO基片上的应变弛豫临界厚度很小,这可能与薄膜-基片之间高的晶格失配率有关.LCMO薄膜的应变弛豫与四方畸变的弛豫可能具有不同的机制.利用掠入射X射线衍射对LCMO薄膜面内生长取向的研究给出了与利用电子显微技术研究相同的结果.     

分子束外延生长ZnO薄膜的XAFS研究

利用同步辐射广延X射线吸收精细结构(EXAFS),研究在不同条件下分子束外延制备的ZnO薄膜,如分别在蓝宝石(0001)、Si(100)衬底上,生长温度为200℃或300℃下得到样品的局域结构。发现这些ZnO薄膜的EXAFS函数(k^2x(k))谱形状相似,说明各个样品都具有较为相近的基本局域结构。对生长温度为200℃的ZnO／Al2O3(0001)和ZnO／Si(100)样品,其Zn-O第一配位峰的无序度仃。分别为0．0054A^2和0．0080A^2,当生长温度从200℃提高到300℃时,ZnO／Al2O3(0001)样品的Zn-O第一配位峰的无序度仃。降为0．0039A^2。结果表明衬底与ZnO的晶格失配度和生长温度对ZnO薄膜的配位数、Zn-O键长影响不大,但较小的晶格失配度和较高的生长温度下得到的ZnO薄膜局域有序性较高;且样品的局域结构越有序,相应的配位峰幅度也越高。     

MOCVD制备的氮化铪薄膜结构特性研究

以热氧化的p型硅(SiO2/Si)为衬底,运用金属有机化学气相淀积(MOCVD)技术以铪基金属有机源和高纯氨为反应气体在其上淀积HfNx薄膜样品。薄膜结构信息用RBS技术、XRD技术及X射线反射率(XRR)计等来表征。实验结果表明,HfNx薄膜中N与Hf原子组分比为1.15;薄膜为多晶薄膜且沿(111)方向择优生长;薄膜表面平整,与衬底界面粗糙度小。     

MAGSUB>3SUP>-/SUP>/SUB>Fol

合成了双功能螯合剂S-乙酰基-巯基乙酸-三甘氨酸-N-羟基丁二酰亚胺酯(S-Acetyl-MAG3-NHS),并以叶酸(folic acid,FA)、乙二胺(ethylenediamine,EDA)和S-Acetyl-MAG3-NHS为原料,合成叶酸配体化合物MAG3-FA;利用酒石酸钠转换配合进行MAG3-FA的99Tcm标记,重点探讨99Tcm标记条件及标记物体外稳定性.结果表明,合成的双功能螯合剂S-Acetyl-MAG3及配体化合物MAG3-FA可成功用于99Tcm的放射性标记,在最佳标记条件下,其标记效率大于70%,经分离纯化后, 99Tcm-MAG3-FA 的放射化学纯度大于95%,标记物体外稳定,为进一步研究99Tcm-MAG3-FA的体内外生物学特性奠定了基础.     

Reactive DC Magnetron Sputter Deposited Titanium-Copper-Nitrogen Nano-Composite Thin Films with an Argon/Nitrogen Gas Mixture

A sintered Ti13Cu87 target was sputtered by reactive direct current (DC) magnetron sputtering with a gas mixture of argon/nitrogen for different sputtering powers. Titanium-copper-nitrogen thin films were deposited on Si (111), glass slide and potassium bromide (KBr) substrates. Phase analysis and structural properties of titanium-copper-nitrogen thin films were studied by X-ray diffraction (XRD). The chemical bonding was characterized by Fourier transform infrared (FTIR) spectroscopy. The results from XRD show that the observed phases are nano-crystallite cubic anti rhenium oxide (anti ReO3) structures of titanium doped Cu3N (Ti:Cu3N) and nano-crystallite face centered cubic (fcc) structures of copper. Scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX) were used to determine the film morphology and atomic titanium/copper ratio, respectively. The films possess continuous and agglomerated structure with an atomic titanium/copper ratio ( 0.07) below that of the original target ( 0.15). The transmittance spectra of the composite films were measured in the range of 360 to 1100 nm. Film thickness, refractive index and extinction coefficient were extracted from the measured transmittance using a reverse engineering method. In the visible range, the higher absorption coefficient of the films prepared at lower sputtering power indicates more nitrification in comparison to those prepared at higher sputtering power. This is consistent with the formation of larger Ti:Cu3N crystallites at lower sputtering power. The deposition rate vs. sputtering power shows an abrupt transition from metallic mode to poisoned mode. A complicated behavior of the films’ resistivity upon sputtering power is shown.     

ION BEAM STUDY ON EPITAXIAL GROWTH FEATURES OF YBaCuO FILMS

The epitaxial growth features of YBa2Cu3O7-x (YBCO) films on (100) SrTiO3 substrates have been studied by Rutherford backscattering spectrometry and axial channeling technique. A typical minimum yield value, Xmin, of Ba yielded in channeling spectrum is 4.6 % for the film of 166 nm. Only (00L) peaks appeared in X ray diffraction patterns of the films. The results indicate that the YBCO films have good epitaxial growth quality with c- axis orientation perpendicular to the substrate surface. Simulation of RB process in films and substrates have also been performed using RUMP program, and analysis shows that compositions of the films are uniform with near (123) stoichiometry. The higher interface yields in the aligned spectrum reveal that there are extra defects in the interface layer owing to lattice mismatch and interface interaction.     

Synthesis of nanostructured multiphase (Ti,Al)N/a-Si3N4 thin films using dense plasma focus device

A 2.3 kJ pulsed plasma focus device was used to prepare thin films of nc-(Ti,Al)N/a-Si₃N₄ at room temperature. The plasma focus device, fitted with copper anode encapsulated with Ti_0.5Al_0.5 anode, was operated with nitrogen as the filling gas. Films were deposited with various number of focus shots, at 90 mm from top of the anode and at zero angular position with respect to anode axis. XRD patterns show the growth of polycrystalline (Ti,Al)N thin films with orientations in the (1 1 1), (2 0 0), (2 2 0) and (3 1 1) crystallographic planes. Behavior of lattice constant, grain size and film roughness of deposited film as a function of variation in number of focus shots is discussed. SEM micrographs of film deposited with 15 number of focus shots exhibit well-developed net like structure of nc-(Ti,Al)N/a-Si₃N₄ and possibly nc-(Ti,Al)N/a-Si₃N₄/a-AlN or nc-TiN/a-Si₃N₄/a-AlN. Surface Roughness ranging 64 nm to 89 nm was also observed.     

Observation of exotic nuclear decay of (230)~U

(230)~Pa was produced through the 232Th(p,3n)230Pa reaction in the irradiated ThO2 powder targets with 35 MeV proton beam. Pa was radiochemically separated from ThO2 and other reaction products, and then thin sources of230Pa→230U were prepared. The polyethylene-terephthalate (lavsan) films were selected as solid track detectorsearching for the cluster activity of 230U. The gamma activity of 230Pa in the sources was measured using a HPGe detector. The lavsan films were etched in NaOH solution and the etched films were scanned under an optical microscope. The exotic nuclear decay of 230U by emission of 22Ne was observed. A branching ratio relative to a decay was deduced, B =λNe/λα = (1.3±0.8)×10~(-14) for 22Ne emission from 230U.     

Large-area deposition of biaxially textured YSZ buffer layers using an IBAD-process

An ion-beam-assisted deposition technique (IBAD), using two Kaufman ion sources with diameters of 11 cm, was employed to grow biaxially textured YSZ buffer layers. They serve as a template for YBCO films and as a diffusion barrier. The best YSZ films on small Al₂O₃ substrates show good in-plane alignment characterized by a FWHM of 10.8° in (111)-Φ-scan. An improvement of texture with rising film thickness was observed saturating at 8.5°. On 100 cm² large substrates the texture was within a range of 15° to 24°. First improvements of the homogeneity were achieved by a four-time rotating of 90° of the substrate holder around the substrate normal during deposition. On polycrystalline PSZ substrates with YSZ buffers YBCO films with a critical current j_c > 10⁶ A/cm² (at 77 K, 0 T) were deposited.     

Preparation and BiologicalEvaluation of Re/99Tcm(CO)3+-diphenyldiazeneDerivative as Candidates for Imaging Aβ Plaques in the Brain

To develop the non-invasiveand diagnostic agents for Alzheimer’s disease (AD), ⁹⁹Tc^m(CO)₃⁺-L(L: (E)-2-(4-((4-(dimethylamino)phenyl)diazenyl)phenylamino)acetic acid, adiphenyldiazene derivative) was prepared,radiochemical purity was above 95%. Initialautoradiography results suggested that ⁹⁹Tc^m(CO)₃⁺-Lshowed selective binding to the Aβ plaque-like structures in the brain section from theAD transgenic mice (Tg C57, APP, PS1 12-month-old), further, ⁹⁹Tc^m(CO)₃⁺-Lshowed the same binding sites with fluorescence stained by Re(CO)₃⁺-L.Biodistribution of ⁹⁹Tc^m(CO)₃⁺-L innormal mice demonstrated low uptake in brain (5 min: （0.52 ±0.11)% ID/g）whilst slow clearance from the brain tissues at 120 min post-injection (0.28 ± 0.04)%ID/g. The corresponding Re analogue was alsosynthesized, and the nature of its lowest electronically excited state wasdetermined by studies of the UV-vis absorption and fluorescence emissionproperties at room temperature. In addition, the fluorescent staining of the Re-complexwas performed in comparison to Thioflavin-T and autoradiography results of ⁹⁹Tc^m(CO)₃⁺-L.In conclusion, these results are encouraging for further exploration of ⁹⁹Tc^m(CO)₃⁺-Las a SPECT imaging agent for Aβplaques in the AD brain.     

Investigation of films of YBa2Cu3O7 using Rutherford backscattering spectrometry

Rutherford backscattering spectrometry (RBS) has been applied to films of the high-temperature superconductor YBa₂Cu₃O₇. The films were prepared by rf and dc sputtering and silk-screen printing onto substrates of alumina, sapphire and magnesia. Some of the samples were exposed to various heat treatments in order to promote the superconducting phase. A 2 MeV beam of He⁺ particles from the 3 MV Dynamitron accelerator at Birmingham University's School of Physics and Space Research was employed for the RBS measurements. The composition and the depth profile of the elements in the films were determined by simulating the observed RBS spectra with a simulation software package. The simulations show that the heat treatment causes marked interdiffusion of the film and substrate. The experimental results and the computer simulations shown in this paper illustrate the advantages of using RBS to characterise films of the new superconducting materials.     

Investigation of conductive and transparent ITO/Ni/ITO multilayer films deposited by a magnetron sputter process

Transparent conducting ITO/Ni/ITO films were deposited by RF magnetron sputtering of Sn-doped In₂O₃ and DC magnetron sputtering of Ni on unheated polycarbonate substrates. Ni interlayers with thicknesses of 5, 10, and 20 nm were used as intermediate metallic layers.Changes in the work function and optical, electrical and structural properties of the films were examined with respect to Ni layer thickness. The work function was measured to be about 4.5 eV and was found to be independent of Ni layer thickness. However, the structural, optical, and electrical properties of the films were influenced by the Ni thickness. As-deposited ITO single layer films showed In₂O₃ diffraction peaks for the (2 2 2) and (4 0 0) planes, while after insertion of the Ni layer between ITO films, these diffraction peaks disappeared. The electrical resistivity decreased with the Ni intermediated film and the optical transmittance also decreased due to increased optical absorption. The figure of merit reached a maximum of 2.0 × 10⁻³ Ω⁻¹ for a 5 nm-thick inserted Ni film, which is greater than the value for as-deposited ITO films.     

Structural and gasochromic properties of epitaxial WO3 films prepared by pulsed laser deposition

The structural and gasochromic properties of epitaxial tungsten trioxide (WO₃) thin films, prepared by ArF excimer pulsed laser deposition under the controlled oxygen atmosphere, have been investigated. The WO₃ films were grown on the α-Al₂O₃ substrates, as the oxygen pressure ranged from 0.57 to 1.20 Pa and the substrate temperature ranged from 432 to 538 °C. The deposited films were characterized by Rutherford backscattering spectroscopy (RBS)/channeling, X-ray diffraction, X-ray pole figures and Raman spectroscopy. RBS and XRD results demonstrated that monoclinic WO₃ (0 0 1) films were successfully grown on the α-Al₂O₃ substrates. The crystal quality was improved by increasing both the oxygen pressure and the substrate temperature. Gasochromic coloration in the WO₃ films by exposure to diluted hydrogen gas was found to correlate with the crystal quality of the films. The gasochromic coloration was suppressed by the epitaxial growth of the films.     

Simulation of thermal stress in Er2O3 and Al2O3 tritium penetration barriers by finite-element analysis

The physical vapor deposition method is an effective way to deposit Al2O3 and Er2O3 on 316L stainless steel substrates acting as tritium permeation barriers in a fusion reactor.The distribution of residual thermal stress is calculated both in Al2O3 and Er2O3 coating systems with planar and rough substrates using finite element analysis.The parameters influencing the thermal stress in the sputter process are analyzed,such as coating and substrate properties,temperature and Young's modulus.This work shows that the thermal stress in Al2O3 and Er2O3 coating systems exhibit a linear relationship with substrate thickness,temperature and Young's modulus.However,this relationship is inversed with coating thickness.In addition,the rough substrate surface can increase the thermal stress in the process of coating deposition.The adhesive strength between the coating and the substrate is evaluated by the shear stress.Due to the higher compressive shear stress,the Al2O3 coating has a better adhesive strength with a 316L stainless steel substrate than the Er2O3 coating.Furthermore,the analysis shows that it is a useful way to improve adhesive strength with increasing interface roughness.