利用ESCADB进行俄歇参数分散图集系统绘制的研究

引言从X射线光电子能谱可以用各种方法鉴定原子的化学价态和化学环境,其中应用最多的是光电子峰的绝对结合能及其化学位移。如果化学位移较小而仪     

俄歇化学位移及其在表面化学上的应用

从俄歇电子激发过程讨论了化学位移和元素化合价以及电负性的关系, 提供了常用元素在不同化合物中的俄歇电子动能及化学位移数据, 运用俄歇化学位移研究了氧在锌表面的吸附和初始氧化反应, Ti/SiO_2的界面固相反应机理以及摩擦过程中润滑膜的组成和结构.     

超高真空俄歇电子能谱原位加热和GaN热效应研究

An in situ heating system was built for the Auger electron spectroscopy to investigate the thermal effect of Auger lines. A GaN sample was studied in this system. The kinetic energy of Ga LMM and MVV Auger lines were observed to shift negatively with temperature increasing. By using ab initio calculation, the theoretical Ga MVV Auger line shape was fit, which well reflects the inner property of the line. The Auger shift with heating is related with the valence electron rearrangement in the thermal expansion of the local bonds.     

应用渐进因子分析法研究SiO_2/Si样品俄歇深度剖析

首次利用渐进因子分析法对ＳｉＯ２／Ｓｉ样品俄歇深度剖析过程进行研究，发现ＳｉＯ２／Ｓｉ界面处有ＳｉＯｘ成分存在，ｘ值在１０～１５之间，厚度约为３０ｎｍ，含量接近５０％。Ａｒ＋离子束的轰击使得ＳｉＯ２薄膜内分解产生亚稳态ＳｉＯ２，含量在１７％左右。研究结果表明，渐进因子分析法非常适合于俄歇深度剖析的化学态分析。     

用俄歇能谱和X射线能谱研究板状碘溴化银微晶中的碘离子的空间分布

本文制备了一系列不同碘含量的板状碘溴化银微晶(微晶大小约为3微米)。运用扫描透射电镜和X射线能谱仪(EDS)对单个微晶进行了分析和研究,半定量地测定了碘离子在板状微晶中的面分布;运用扫描俄歇微区棵针(SAM)和二次电子像、离子溅射剥层技术对微晶进行了表面及其纵深的碘离子的点分析,根据EDS和SAM的结果,可以得到板状碘溴化银微晶中的碘离子的空间分布。实验结果表明在板状缺溴化银微晶中,在其中心部位的碘含量最高;越靠近横向边缘的位置,碘含量越低。且在制备碘溴化银微晶时,如果pAg值较高,将会使在制备早期加入的碘离子通过不断的重结晶向微晶表面扩散,得到的微晶不是夹心结构的碘溴化银微晶。     

MoO3在Al2O3薄膜表面扩散的研究

氧化物和盐类在高比表面载体上的单层分散现象已被大量实验所证实［１］．ＭｏＯ_３在γ－Ａｌ_２Ｏ_３等高比表面载体上的分散已经研究很多,近来的研究证实ＭｏＯ３等在α－Ａｌ２Ｏ３等小比表面载体上也能自发单层分散［２］,但是分散的过程仍然缺乏直接的观察研究．本工作通过多种表面分析方法首次研究了ＭｏＯ３在平整无定形的Ａｌ２Ｏ３薄膜上的扩散过程以及影响因素．发现除温度升高外、水汽的存在对该扩散过程也有促进作用．１实验部分１．１样品的制备采用ＳＳ－３２００真空磁控溅射镀膜机,通入Ａｒ－Ｏ２作为反应气,直流磁控…     

角分辨飞行时间法研究GaAs(100)表面蚀刻反应动力学

采用探测室可转动的分子束实验装置,研究了氯分子束与GaAs(100)表面热反应和紫外激光诱导反应的动力学.结果表明,热反应的主要产物为GaCl~3, 其角分布可用cos^2^.^3θ函数拟合.对于紫外(355nm)激光诱导反应,由角分辨的飞行时间(TOF)法测得主要产物为GaCl等,它们的通量角分布须用双余弦加和公式(c~1cosθ+c~2cos^nθ)拟合,表示产物粒子在表面法线方向明显聚集,而且由TOF 谱求得粒子的动能在表面法线方向最大. 这种明显的聚集现象可以由激光诱导的粒子在表面附近发生碰撞效应来解释     

HCOO在Cu(110)、Ag(110)和Au(110)表面的吸附

采用密度泛函理论(DFT)以及广义梯度近似方法(GGA)计算了甲酸根(HCOO)在Cu(110)、Ag(110)和Au(110)表面的吸附. 计算结果表明, 短桥位是最稳定的吸附位置, 计算的几何参数与以前的实验和计算结果吻合. 吸附热顺序为Cu(110)(-116 kJ·mol-1)>Ag(110)(-57 kJ·mol-1)>Au(110)(-27 kJ·mol-1), 与实验上甲酸根的分解温度相一致. 电子态密度分析表明, 吸附热顺序可以用吸附分子与金属d-带之间的Pauli 排斥来关联, 即排斥作用越大, 吸附越弱. 另外还从计算的吸附热数据以及实验上HCOO的分解温度估算了反应CO2+1/2H2→HCOO的活化能, 其大小顺序为Au(110)>Ag(110)>Cu(110).     

Evaluation of Auger Electron Spectroscopy (AES) depth-profiles by application of Factor Analysis

Summary AES is a useful tool in order to determine the quantitative composition of a solid surface. Conventional methods of evaluating AES concentration profiles leave chemical information about the bonding state of an element contained in the spectra unused. To extract these Factor Analysis (FA) was employed as a mathematical technique to form a physical model of the composition of a sample. With FA the correlation function between the measured spectra is evaluated. Thus it is possible to determine number and quantity of chemical components influencing the data. The feasibility of FA is demonstrated by its application to the evaluation of AES concentration profiles. We investigated in some detail heterostructures consisting of a Si₃N₄/-Si:H/SiO₂ and Ti/Si Schottky contacts on Si substrates, respectively.     

Influence of Glycine Adsorption on Segregation of Ni-Cu (110) Surface

An atomic group model of the disordered binary alloy NixCu1-x (x=0.4) was constructed to investigate surface segregation. According to the model, the electronic structure of the NixCu1-x alloy surface was calculated by the Recursion method when glycine atoms are adsorbed on the NixCu1-x (110) surface under the condition of 0.33 coverage. The calculation results indicate that Cu is segregated on the surface of the NixCu1-x alloy, and the chemisorption of glycine restrains the segregation. In addition, the chemical adsorption of glycine greatly changes the density of states of the alloy surface near the Fermi level, and there is electric charge transfer between the alloy surface and the glycine.     

A Density Functional Study of Ozone and Oxygen Surface Structures on Ni(110)

The dissociative and molecular forms of O₃ adsorbed on nickel were studied by the density functional method (Becke3LYP exchange correlation functional). The energy profile of the ozone decomposition reaction (O₃)_gas (O₃)_ads (O₂)_ads+1/2O₂ on the Ni₁₀ surface cluster was calculated. As opposed to the weakly bound molecular form of oxygen on transition metals, ozone forms a tightly bound surface compound on the surface of nickel. It is attempted to evaluate the heat of oxygen adsorption on the defective surface of Ni using the model of the surface cluster Ni₁₃ with a vacancy . The positions of the surface nickel atoms before and after their interaction with the adsorbate were calculated. It is shown that substantial relaxation of the surface nickel atoms takes place in the course of adsorption. The possibility of stabilization of the molecular ozone-like form of oxygen on the surface of transition metals in conditions of high oxygen coating extent is discussed.     

Depth profile investigations of metallic layer contacts to GaAs(100) and InP(100) by means of Auger Electron Spectroscopy and sputter technique

Summary The present technological development in the field of opto-electronics requires a sufficiently high stability of the applied metal-semiconductor contacts because of the thermal and electrical cross-section loading. Au/Pt/Ti layer contacts to GaAs(100) and InP(100) substrates annealed under various conditions were investigated by means of Auger Electron Spectroscopy (AES) in conjunction with ion sputtering. The diffusion and reaction behavior are discussed based on intensity-depth profiles and chemical shifts. As the main result we found that the GaAs contact is more stable. It reacts strongly at a temperature of about 450°C. On the other hand Au/Pt/Ti/InP contact reacts already above 300°C. The principal reason for the difference in the behavior of InP and GaAs contacts is the In segregation.     

密度泛函理论预测微量元素在Al(100)表面的偏聚

通过周期性层状模型, 利用密度泛函理论预测了微量杂质元素原子M(M=Fe, Si, Mg, Cu, Mn, Ga, In, Sn, Pb)在高纯铝箔(100)表面的偏聚趋势. 计算得到表面偏聚能与已有实验结果相吻合. 表面偏聚能由表面取代的微量元素原子M的位置、原子半径和金属的表面能决定. 当表面偏聚能为负时, 微量元素原子M在表面偏聚, 反之则杂质原子不发生表面聚集. 微量元素原子在铝箔表面偏聚可以使铝箔表面产生大量的缺陷和位错, 它们在铝箔腐蚀时容易成为腐蚀的形核起点, 进而增加铝箔的腐蚀发孔密度.     

以芳香族多羧酸为配体的Ni(II)配位超分子的研制及光诱导下的表面电子行为

采用水热方法合成了2个Ni(II)配合物[Ni3(btc)2(H2O)14]·4H2O(1)和[Ni2(btec)(bipy)2(H2O)6]·2H2O(2), (H3btc=1,3,5-benzenetricarboxylic acid, H4btec=1,2,4,5-benzenetetracarboxylic acid, bipy=2,2'-bipyridyl). 通过X射线单晶衍射(XRD)、红外光谱(IR)、紫外-可见-近红外吸收光谱(UV-Vis-NIR)对化合物进行了表征. 结果表明, 化合物(1)是由2个均苯三甲酸根桥连的三核Ni(II)离子的化合物, 而化合物(2)是由1个均苯四甲酸根桥连的双核化合物, 分子中bipy分子作为端基配体. 分子中大量的水分子和羧酸根的存在使2个化合物分别被连成具有三维(3D)和二维(2D)结构的配位超分子化合物. 着重研究了化合物的表面光电压光谱(SPS), 并将其与UV-Vis-NIR吸收光谱进行了分析和对比, 发现SPS 中表面光伏响应带与UV-Vis-NIR 吸收光谱的吸收峰在数量和位置上都是一一对应的. 此外, 对比2个化合物的表面光电压光谱可以看出,配合物的结构及中心金属的配位微环境对其表面光伏响应带的强度、位置和形状均有一定影响.     

TiO2单晶的表面光电压谱研究

TiO2由于其优异的光电性质及高的化学稳定性而受到广泛关注,并且被应用于有机污染物光降解[1]、太阳能光电转换[2]等诸多领域.由于制备方法不同,TiO2往往会呈现出不同的光电性质,尽管其晶型与粒度可能相差甚微[3].近年来研究表明,除晶型、粒度等因素外,表面原子排布在决定材料光电性质方面同样有重要贡献[4,5].本文采用表面光电压谱(SPS)及场诱导表面光电压谱(EFSPS)研究了TiO2单晶(001)面的光伏响应.