薄膜特性的掠发射X射线荧光分析

掠射X射线荧光分析技术是实验室分析薄膜特性的一种重要工具。文章简述了利用掠出射X射线荧光技术分析薄膜厚度的原理和方法,介绍了一种可在实验室里实现薄膜特性测试的掠发射X射线荧光分析装置,该装置采用波长色散方式结合超薄窗流气正比计数管,可实现对轻元素的探测。最后从理论上计算了Si片上不同厚度的几种单层薄膜的X射线荧光强度和掠出射角的依赖关系。证明了掠发射X射线荧光分析是一种精确的分析薄膜厚度等特性的方法。     

掠出射X射线荧光分析方法

报道了由中国科学院高能物理研究所自行研制的掠出射X射线荧光分析(GEXRF)装置.掠出射X射线荧光分析不仅可以测量薄膜的成分, 而且可确定薄膜的厚度, 密度和化学成分随深度的变化.利用该装置, 在X射线发生器和北京同步辐射装置上, 对硅基体上的金属薄膜(Ni, Ni/Ti)和砷化镓晶体进行了掠出射X射线荧光分析. 所得结果表明, 掠出射X射线荧光分析是一种分析薄膜厚度, 密度等特性的有力工具.     

掠出射X射线荧光分析

掠出射X射线荧光分析技术是全反射X射线荧光分析技术的延伸和发展，文章介绍了掠出射X射线荧光分析技术的形式，特点，基本原理和作者在实验室搭建的实验装置，简述了掠出射X射线荧光分析技术的发展史，以及该技术在化学元素微量和痕量分析及薄膜特性分析等领域中的应用，展望了这种技术今后的发展前景。     

掠出射X射线荧光谱仪性能评测

通过对GaAs(100)抛光晶片在相同条件下掠出射X射线荧光实验的可重复性研究,并结合常规光源与同步辐射光源X射线掠出射荧光实验结果的对比,证明自行研制的掠出射X射线荧光平台可重复性较好,稳定性较高,实验方法的设计是合理的。理论计算与实验曲线符合的较好,证明掠出射X射线荧光实验中用单晶的全反射临界角标定掠出射角度的方法是可行的。用标准晶片掠出射X射线荧光曲线的微分评测了实际角发散度的大小。     

射线探测技术与装置

依据工作原理,比较了掠出射X射线荧光分析技术(GEXRF)和掠人射X射线荧光分析技术(Gl一XRF)的优缺点,比较角度包括实验装置、探测限、可探测元素范围、基体效应以及实验精度。比较结果表明,GEXRF的优点体现为:对实验装置要求低,对轻元素(4相似文献   

X射线荧光光谱检测多层薄膜样品的增强效应研究

研究了X射线荧光光谱检测多层薄膜样品的增强效应。根据多层膜中的X荧光强度理论计算公式编写了计算机程序,并计算了Zn/Fe和Fe/Zn双层膜样品中不同薄膜厚度时Fe Kα的一次荧光强度、二次荧光强度、二次荧光与一次荧光强度比以及二次荧光在总荧光强度中比例。研究发现,在多层膜样品的X射线荧光分析中,激发条件不变的情况下,元素谱线的一次荧光相对强度、二次荧光相对强度和二次荧光在总荧光强度中所占比例都随薄膜厚度及位置的变化而变化。当Fe和Zn层厚度相同时,随厚度的变化,对于Fe/Zn样品,Fe Kα二次荧光强度占总荧光强度最高为9％,而对于Zn/Fe样品这一比例最高可达35％。     

硬X射线微束掠入射实验的控制和数据采集系统及其应用

在国内发展了硬X射线微束掠入射实验方法,并将此具有微米级高空间分辨率的方法应用于纳米厚度薄膜的微区分析。该实验方法对分析样品表面或薄膜在微小区域的不均匀组分、结构、厚度、粗糙度和表面元素化学价态等信息具有重要意义。基于X射线全反射原理,以微聚焦实验站的高通量、能量可调的单色微束X射线为基础,通过集成运动控制、光强探测、衍射和荧光探测,设计了掠入射实验方法的控制和数据采集系统。此系统采用分布式控制结构,并基于Experimental Physics and Industrial Control System （EPICS）环境设计SPEC控制软件。通过建立SPEC和EPICS的访问通道,实现SPEC软件对EPICS平台上设备的控制和数据获取。在所设计的控制和数据采集系统中,运动控制系统控制多维样品台电机的运动,实现定位样品位置和调节掠入射角;光强探测系统则监测样品出射光强度,通过样品台运动控制和光强探测的联控,实现样品台的扫描定位控制;通过衍射和荧光探测系统获取不同入射深度下样品的衍射峰强度和荧光计数。此外,为准确控制掠入射角角度,必须确定样品平面与X射线平行的零角度位置,对此给出一种自动定位零角度的方法,编写了该方法的控制算法,设计了相应的控制软件。零角度自动化定位的扫描结果表明,实验系统微区分析的空间分辨率达到2.8 μm,零角度定位精度小于±0.01°。利用该系统在上海光源微聚焦实验站首次实现了具有自动化准确控制零角度的微束掠入射X射线衍射和荧光同步表征的实验方法,实验中被测样品为10 nm Au/Cr/Si薄膜材料,Si基底最上层为10 nm厚的Au薄膜,其间为一层很薄的Cr粘附层。在不同掠入射角下测量样品的衍射信号,获取不同入射深度下样品的衍射峰强度,并实现在同一掠入射角下,同步采集样品的荧光计数信号,从而确定了样品表层的相结构信息以及荧光信号强度与入射角关系,实现了对纳米厚度薄膜在微小区域的相结构和组分分析。此外,通过该技术能够选取荧光计数最大值对应的入射角度,有助于提高后续发展的低浓度样品掠入射X射线吸收近边结构实验方法的信噪比。     

X射线W/B4C宽带多层膜的优化设计和制备

介绍了X射线宽带多层膜材料W和B4C的选定方法,依据伯宁(BERNING)公式确定出了在0.154 nm处X射线宽带多层膜的最佳膜对数。引入适当的评价函数,利用具有全局寻优特性且效率较高的遗传算法,在波长0.154 nm处优化设计出了掠入射角(θ)0.5°~0.9°范围内反射率值达到40%的宽角度宽带多层膜。宽带多层膜反射镜采用磁控溅射方法制备,并用X射线衍射仪对样品进行了检测,结果表明在掠入射角(2θ)1.0°~1.8°之间的相对反射率光谱曲线比较平坦。     

掠射技术与X射线荧光分析

掠射技术引入Ｘ射线荧光分析成为一种新的材料及薄膜分析技术。运用此技术命同材料表面及薄膜的密度、厚度、界面粗糙度、成分的深度和剖面分布等各种信息，本文介绍了掠射技术在Ｘ射线荧光分析中的应用及近年来的发展和前景。     

极紫外与软X射线用非晶碳膜全反射镜的研究

用高真空磁控溅射设备分别在工作气压为0.40Pa和0.67Pa下制备了非晶碳膜全反射镜样品,利用X射线掠入射反射测量了膜层厚度、粗糙度和膜层密度,用原子力显微镜测量了样品的表面粗糙度,用同步辐射测量了不同工作气压下制备的非晶碳膜全反射镜的反射率,并对测量结果进行了分析讨论.测试结果表明:在0.40Pa工作气压下制备的非晶碳膜反射镜的性能优于在0.67Pa工作气压下制备的反射镜的性能,在掠入射角小于4.5°时,非晶碳膜全反射镜在5nm以上波段有比较平坦的高反射率,在波长小于5nm波段,反射率急剧下降.     

基于X射线掠射法的纳米薄膜厚度计量与量值溯源研究

为了实现纳米薄膜厚度的高精度计量,研制了可供台阶仪、扫描探针显微镜等接触测量的纳米薄膜样片,研究了X射线掠射法测量该纳米薄膜样片厚度的基本原理和计算方法,导出了基于Kiessig厚度干涉条纹计算膜层厚度的线性拟合公式,并提出了一种可溯源至单晶硅原子晶格间距和角度计量标准的纳米膜厚量值溯源方法,同时给出了相应的不确定度评定方法.实验证明:该纳米薄膜厚度H测量相对扩展不确定度达到U=0.3 nm+1.5%H,包含因子k=2.从而建立了一套纳米薄膜厚度计量方法和溯源体系.     

一种可溯源的光谱椭偏仪标定方法

提出了一种用X射线反射术标定光谱椭偏仪的方法.作为一种间接测量方法,光谱椭偏术测得的薄膜厚度依赖于其光学常数,不具有可溯源性.在掠入射条件下,X射线反射术能测得薄膜的物理厚度,测量结果具有亚纳米量级的精密度且与薄膜光学常数无关.在单晶硅基底上制备了厚度分别为2nm,18nm,34nm,61nm及170nm的SiO2薄膜标样,并用强制过零点的直线拟合了两种方法的标样测量结果,拟合直线的斜率为1.013±0.013,表明该方法可在薄膜厚度测量中标定光谱椭偏仪.     

Morphology of open films of discotic hexagonal columnar liquid crystals as probed by grazing incidence X-ray diffraction

The structure and the orientation of thermotropic hexagonal columnar liquid crystals are studied by grazing incidence X-ray diffraction (GIXD) for different discotic compounds in the geometry of open supported thin films. Whatever the film deposition mode (either spin-coating or vacuum evaporation) and the film thickness, a degenerate planar alignment with the liquid crystalline columns parallel to the substrate is found. However, if a specific thermal process is applied to the liquid crystal film, homeotropic anchoring (columns normal to the interface) can be stabilized in a metastable state.     

The surface hydro-oxidation of LaNiO(3-delta) thin films

The chemical structure and possible hydro-oxidation of LaNiO(3-delta) films were studied by means of tuneable high-energy X-ray photoelectron spectroscopy using synchrotron radiation. It was shown that the hydroxyl-containing phase, located near the film surface, may be attributed to the lanthanum and nickel hydroxide species. The thickness of a hydroxide-enriched layer was estimated from the oxide/hydroxide ratio measured at normal and grazing conditions. The hydroxide layer thickness was about 2 nm for step and/or exponential hydroxide spatial distribution.     

Realisation and metrological characterisation of thickness standards below 100 nm

High-accuracy film thickness measurements in the range below 100 nm can be made by various complex methods like spectral ellipsometry (SE), scanning force microscopy (SFM), grazing incidence X-ray reflectometry (GIXR), or X-ray fluorescence analysis (XRF). The measurement results achieved with these methods are based on different interactions between the film and the probe. A key question in nanotechnology is how to achieve consistent results on a level of uncertainty below one nanometre with different techniques.Two different types of thickness standards are realised. Metal film standards for X-ray techniques in the thickness range 10 to 50 nm are calibrated by GIXR with monochromatised synchrotron radiation of 8048 eV. The results obtained at four different facilities show excellent agreement. SiO₂ on Si standards for SE and SFM in the thickness range 6 to 1000 nm are calibrated by GIXR with monochromatised synchrotron radiation of 1841 eV and with a metrological SFM. Consistent results within the combined uncertainties are obtained with the two methods. Surfaces and interfaces of both types of standards are additionally investigated by transmission electron microscopy (TEM). PACS 61.10.Kw; 68.55.Jk; 06.20.Fn; 06.60.Mr; 07.79.Lh     

溅射银超细微晶膜分析

采用真空溅射沉积技术在硅单晶Si（111）面上制备厚度约为18nm的银超细微晶膜（AgUFCP）．用掠入射X射线散射技术分析了AgUFCP的结构和膜与衬底Ag/Si（111）界面形态．用广角X射线衍射和径向分布函数探索了AgUFCP的半晶态结构特征．用差热扫描量热法检测分析了银超细微晶粒子的表面原子结构，揭示了超细微晶粒子表面生长的热动力学机理对表面壳层结构的温度依赖性． 关键词：     

Grazing incidence X-ray studies of ultra-thin Lumogen films

Lumogen^® Yellow S0790 films have been produced on silicon wafer substrates via physical vapour deposition (PVD) and spin-coating (SC) methods. These coatings were characterised with X-ray reflectometry (XRR) and grazing incidence X-ray diffraction (GIXD) techniques. The results show that ultra-thin (less than 12 nm) PVD films coat amorphously, with crystallinity becoming increasingly apparent with increasing film thickness. In contrast, measurements of ultra-thin (less than ∼2 nm) spin-coated films reveal a second, apparently stable crystalline structure.     

Structural characterization of supported nanocrystalline ZnO thin films prepared by dip-coating

Nanocrystalline ZnO thin films prepared by the sol-gel dip-coating technique were characterized by grazing incidence X-ray diffraction (GIXD), atomic force microscopy (AFM), X-ray reflectivity (XR) and grazing incidence small-angle X-ray scattering (GISAXS). The structures of several thin films subjected to (i) isochronous annealing at 350, 450 and 550 °C, and (ii) isothermal annealing at 450 °C during different time periods, were characterized. The studied thin films are composed of ZnO nanocrystals as revealed by analysing several GIXD patterns, from which their average sizes were determined. Thin film thickness and roughness were determined from quantitative analyses of AFM images and XR patterns. The analysis of XR patterns also yielded the average density of the studied films. Our GISAXS study indicates that the studied ZnO thin films contain nanopores with an ellipsoidal shape, and flattened along the direction normal to the substrate surface. The thin film annealed at the highest temperature, T = 550 °C, exhibits higher density and lower thickness and nanoporosity volume fraction, than those annealed at 350 and 450 °C. These results indicate that thermal annealing at the highest temperature (550 °C) induces a noticeable compaction effect on the structure of the studied thin films.