分析薄膜厚度与成分的卢瑟福背散射技术

对卢瑟福背散射分析技术的基本原理、试验设备、样品要求及数据处理方法进行了介绍,并举例分析了硅衬底上钛膜厚度的测定,以及钼衬底上钛钼合金膜的实际组分以及氦离子注入杂质的分布范围和实际剂量测定。讨论了卢瑟福背散射技术的发展和应用,介绍了弹性反冲、高能非卢瑟福散射和沟道技术三种分析方法。     

前向反冲分析和非卢瑟福背散射

介绍了弹性散射分析中的另外两种分析方法——前向反冲分析和非卢瑟福背散射分析。前向反冲分析适用于材料中H和He同位素分析。高能质子和He离子背散射分析可提高对重基体中C,N和O等轻元素分析的灵敏度。给出了这两种分析方法的应用实例。     

氮化铁梯度薄膜的制备

用对向靶溅射仪制备了具有梯度结构的氮化铁薄膜材料．卢瑟福背散射分析结果表明，铁、氮两种原子的密度沿膜厚度方向呈梯度变化．在薄膜中有ζ－Ｆｅ２Ｎ，ε－ＦｅｘＮ（２＜ｘ＜３），γ′－Ｆｅ４Ｎ和α″－Ｆｅ１６Ｎ２等物相．振动样品磁强计测试结果表明部分梯度膜的饱和磁化强度值接近纯铁膜，膜面富铁的梯度样品的矫顽力与基底富铁的梯度样品的矫顽力相差很大。     

采用光致发光法和卢瑟福背散射法测定AIxGa1-xN薄膜中的Al元素含量及斯托克斯移动研究

采用深紫外光致发光技术测量AIxGa1-xN半导体薄膜的禁带宽度,结合软件模拟计算AIxGa1-xN薄膜的弯曲因子b,测定了AIxGa1-xN薄膜中的Al元素含量,同时采用卢瑟福背散射技术测定AIxGa1-xN薄膜中的Al元素含量。结果显示,AIxGa1-xN薄膜的激发光谱和吸收光谱测得的禁带宽度一致,说明AIxGa1-xN薄膜中不存在斯托克斯移动,由MaterialStudio软件计算得到弯曲因子b为1．01eV,符合理论值;在卢瑟福背散射测量中,模拟谱和随机谱重合较好,能够准确测得灿元素含量。两种方法测定的AIxGa1-xN外延膜样品中的A1组分含量基本一致,光致发光法结果比背散射法结果稍大,而且Al含量越小,测量结果越吻合。     

采用光致发光法和卢瑟福背散射法测定Alx Ga1－x N薄膜中的Al元素含量及斯托克斯移动研究

采用深紫外光致发光技术测量AlxGa1－xN半导体薄膜的禁带宽度,结合软件模拟计算AlxGa1－xN薄膜的弯曲因子b,测定了Alx Ga1－x N薄膜中的Al元素含量,同时采用卢瑟福背散射技术测定Alx Ga1－x N薄膜中的Al元素含量。结果显示,Alx Ga1－x N薄膜的激发光谱和吸收光谱测得的禁带宽度一致,说明Alx Ga1－x N薄膜中不存在斯托克斯移动,由Material Studio软件计算得到弯曲因子b为1.01eV,符合理论值;在卢瑟福背散射测量中,模拟谱和随机谱重合较好,能够准确测得Al元素含量。两种方法测定的Alx Ga1－x N外延膜样品中的Al组分含量基本一致,光致发光法结果比背散射法结果稍大,而且Al含量越小,测量结果越吻合。     

精确测定In_xGa_(1-x)N晶体薄膜中铟含量的卢瑟福背散射法研究

采用金属有机化合物气相淀积法(MOCVD)在蓝宝石上生长InxGa1-xN/Ga N晶体薄膜,Ga N缓冲层的厚度为2.5μm,InxGa1-xN晶体薄膜的厚度大约800 nm,通过光致发光光谱仪测量样品发光峰的峰值,确定铟镓氮晶体薄膜中铟分布的均匀性,取样品均匀性良好的铟镓氮晶片进行卢瑟福背散射实验,每个实验室测量6个样品,两个实验室共同完成,对数据进行分多层精确拟合分析,获得外延层中的xIn,xIn值由多层拟合结果的加权平均值和定值不确定度组成。研究结果表明:采用入射离子4He,能量为2 000 ke V,散射角为165°时,铟镓氮晶片中铟含量(x=20.46%)的相对测量不确定度为2.47%,包含因子k=2。     

电子背散射衍射技术及其在材料分析中的应用

较详细地阐明了电子背散射衍射技术（EBSD）的基本原理、实验分析方法。通过安装在场发射扫描电子显微镜上的电子背散射衍射系统,可以对块状样品进行材料微区范围内取向与结构的快速分析,使显微组织、微区成分与结晶学数据分析联系起来,电子背散射衍射技术成为现代材料科学研究的重要实验技术。     

ADS系统中子散裂靶的传热分析

在加速器驱动的次临界核能系统（简称ADS）的研究中，中子散裂靶的散热是一个重要的课题。本文阐述了散裂靶的选择，并利用LAHET程序模拟高能质子引起靶核散裂的过程，计算靶中的能量沉积，以及利用PHOENICS程序，在不同的功率状态对固体靶区进行散热分析。结果表明，在靶区功率较高的情况下，固体靶的传热效果差。因此，使用液体靶，将是更合理的选择。     

基于多分辨率分析的数字图像自动聚焦算法研究

本文提出一种基于小波变换的多分辨率分析方法来实现数字图像自动聚焦的新算法。本算法通过对小波变换后清晰图像和模糊图像的高频系数的能量值进行计算比较，从而可以判断图像是否聚焦。计算机仿真也证实了该算法的正确性和有效性。     

基于能量动量方法的空间薄膜结构的展开分析

基于能量、动量以及动量矩(角动量)守恒定律,该文对传统的拉格朗日方程进行了修正,将能量动量法应用于空间薄膜结构的展开分析中,该方法不仅保证了计算的精度和数值积分的稳定,而且在薄膜的非线性变形分析中,将小刚度模型引入薄膜的褶皱松弛分析,同时考虑了气体的热力学性能、气体与薄膜的耦合作用以及薄膜的自接触等问题.通过对充气管的...     

NiTi thin film characterization by Rutherford backscattering spectrometry

Nickel and titanium can form alloys showing the shape memory effect when combined in the right stoichiometric proportion (1:1). Recently, such alloys have been produced as thin films by sputtering (RF or DC, with or without magnetron), with a view to making microelectromechanical actuators. Precise control of the characteristic transformation temperature is crucial for obtaining the shape memory effect. This requires analytical tools which can accurately determine the relative composition, and hence the transition temperature. In this paper, Rutherford backscattering spectrometry will be shown to meet the requirements of thin film processing of NiTi shape memory alloys, and to have advantages when compared with other techniques.     

Measurement of epitaxial misorientations and related effects in thin films of YBa2Cu3O7-δ grown on nominally (001)MgO substrates by pulsed laser deposition

Heteroepitaxial YBa₂Cu₃O_7-δ thin films have been deposited onto nominal (001)MgO substrates by pulsed laser deposition. For some of these films, Rutherford backscattering spectrometry analysis revealed anomalous variations in the backscattered yield at the substrate level during [001] YBa₂Cu₃O_7-δ axial channelling. A novel angular-dependent ion channelling technique has been developed to investigate these effects. It has been shown that the anomalies arise from an epitaxial misorientation between the lattices of the substrate and deposit. Strong correlations were found between the magnitudes of the misorientations, the densities of spiral features on the deposit surface and the critical current densities exhibited by the deposits. It is proposed that the misorientation arises due to vicinal offcut of the substrate surface, which leads to a lower density of threading dislocations and hence less flux pinning.     

多晶薄膜及表面层的XRD分析方法讨论

对多晶薄膜XRD分析的基本问题小角度衍射几何、非对称平行光束法和Seemann－Bohlin法的衍射几何强度计算，以及P－B法、S－B法对常规XRD分析的适应性进行了分析讨论。并对多晶薄膜XRD分析的当前进展、难点及发展作了分析。提出两种薄膜及表面层表征参量沿深度方向变化的情况下进行XRD深度分布分析的新方法，该方法具有真实深度尺度和定量的特点，并可用于界面分析。     

Metal Organic Chemical Vapour Deposited Thin Films of Cobalt Oxide Prepared via Cobalt Acetylacetonate

The single solid source precursor, cobalt (Ⅱ) acetylacetonate was prepared and characterized by infrared spec-troscopy. Thin films of cobalt oxide were deposited on soda lime glass substrates through the pyrolysis (metal organic chemical vapour deposition (MOCVD)) of single solid source precursor, cobalt acetylaceto-nate, Co[C5H7O2]2 at a temperature of 420℃. The compositional characterization carried out by rutherford backscattering spectroscopy and X-ray diffraction (XRD), showed that the films have a stoichiometry of Co2O3 and an average thickness of 227±0.2 nm. A direct energy gap of 2.15±0.01 eV was calculated by the data obtained by optical absorption spectroscopy. The morphology of the films obtained by scanning electron mi-croscopy, showed that the grains were continuous and uniformly distributed at various magnifications, while the average grain size was less than 1 micron for the deposited thin films of cobalt oxide.     

Surface modification by laser etching using a surface-adsorbed layer

The high-precision, low-damage patterning by laser-induced back side etching techniques is still of interest, particularly for ultra-precision engineering, although the mechanism is not yet clear. The drastically altered optical properties of fused silica etched with LESAL (laser etching at a surface-absorbed layer) give evidence for the etching mechanism. Depth-resolved UV/Vis spectroscopic measurements show that the modified layer is limited to a depth of ~ 60 nm. This is correlated with a very high calculated absorption coefficient of ~ 4 × 10⁷ m^− 1 of the modified surface layer. With Rutherford backscattering spectrometry (RBS) measurements on LESAL-modified surfaces, it was demonstrated that in dependence on the laser fluence used, an amorphized layer with a thickness of a few nanometers was generated. The RBS measurements show that carbon is incorporated into the LESAL-modified surface.     

Superior Stable and Long Life Sodium Metal Anodes Achieved by Atomic Layer Deposition

Na‐metal batteries are considered as the promising alternative candidate for Li‐ion battery beneficial from the wide availability and low cost of sodium, high theoretical specific capacity, and high energy density based on the plating/stripping processes and lowest electrochemical potential. For Na‐metal batteries, the crucial problem on metallic Na is one of the biggest challenges. Mossy or dendritic growth of Na occurs in the repetitive Na stripping/plating process with an unstable solid electrolyte interphase layer of nonuniform ionic flux, which can not only lead to the low Coulombic efficiency, but also can create short circuit risks, resulting in possible burning or explosion. In this communication, the atomic layer deposition of Al₂O₃ coating is first demonstrated for the protection of metallic Na anode for Na‐metal batteries. By protecting Na foil with ultrathin Al₂O₃ layer, the dendrites and mossy Na formation have been effectively suppressed and lifetime has been significantly improved. Furthermore, the thickness of protective layer has been further optimized with 25 cycles of Al₂O₃ layer presenting the best performance over 500 cycles. The novel design of atomic layer deposition protected metal Na anode may bring in new opportunities to the realization of the next‐generation high energy‐density Na metal batteries.     

Atomic layer deposition of MnO using Bis(ethylcyclopentadienyl)manganese and H2O

Manganese oxide (MnO) atomic layer deposition (ALD) was accomplished using sequential exposures of bis(ethylcyclopentadienyl)manganese (Mn(CpEt)₂) and H₂O. Rutherford backscattering analysis revealed a nearly 1:1 atomic ratio for Mn:O in the MnO ALD films. X-ray diffraction determined that the films were crystalline and consistent with the cubic phase of MnO. Quartz crystal microbalance (QCM) measurements monitored the mass deposition rate during MnO ALD and verified self-limiting reactions for each reactant. Extremely efficient reactions were observed that required reactant exposures of only 3 × 10⁴ L (1 L = 1.33 × 10^− 4 Pa s). X-ray reflectivity (XRR) studies were used to confirm the QCM measurements and determine the film density and film thicknesses. The MnO ALD film density was 5.23 g/cm³. The growth per cycle was investigated from 100-300 °C. The largest MnO ALD growth per cycle was 1.2 Å/cycle at 100 °C and the growth per cycle decreased at higher temperatures. Transmission electron microscopy images observed the conformality of MnO films on ZrO₂ nanoparticles and confirmed the growth per cycle observed by the XRR studies. Fourier transform infrared spectroscopy was used to study the -CpEt? and -OH? surface species during MnO ALD and also monitored the bulk vibrational modes of the growing MnO films. The results allowed a growth mechanism to be established for MnO ALD using Mn(CpEt)₂ and H₂O. Only 54% of the Mn sites are observed to retain the -CpEt? surface species after the Mn(CpEt)₂ exposure. Efficient MnO ALD using Mn(CpEt)₂ and H₂O should be useful for a variety of applications where metal oxides are required that can easily change their oxidation states.     

Determination of dopant concentration in co-deposited organic thin films by using RBS and X-ray fluorescence combined techniques

Organic light emitting diodes using phosphorescent dyes (PHOLEDs) have excellent performance and an internal quantum efficiency approaching 100%. To maximize performance, PHOLED devices use a conductive organic host material with a phosphorescent guest that is sufficiently dispersed to avoid concentration quenching. One of the most widely used organic compounds, green phosphorescent fac-tris(2-phenylpyridine)iridium, or [Ir(ppy)₃], can be used to produce PHOLEDs with very high external quantum efficiency by doping host material at different nominal concentrations. In this study, a methodology to accurately establish dopant concentration in co-deposited organic layers is proposed and discussed. X-ray fluorescence (XRF) and Rutherford backscattering (RBS) analyses were performed in co-deposited organic thin films and then combined to provide an accurate methodology. [Ir(ppy)₃] was used at different concentrations in two different hosts – 2,7-bis(9-carbazolyl)-9,9-spirobifluorene (Spiro2-CBP) and copper phthalocyanine (CuPc) – to test the proposed methodology. As Cu peak is easily detected by RBS, the CuPc host was chosen for calibration purposes, allowing more accurate determination of [Ir(ppy)₃] concentration. A linear correlation between the RBS and the XRF measurement data was found allowing the drawing up of a calibration chart used to determine the [Ir(ppy)₃] mass content in co-deposited films.