俄歇定量分析中确定背散射因子的一种新方法

背散射因子是俄歇定量分析中要考虑的主要因素。本文提出一种利用微分前俄歇谱N(E)背景求得背散射因子的新方法。由于使背散射因子的计算与能谱相结合,这种方法不但可以避免Monte Carlo的冗长计算,还能进一步提高定量分析的精度。文中列举了用该方法对Au-Cu和Ag-Cu两种合金的定量分析结果,并与Monte Carlo和相对灵敏度因子方法的结果进行了比较。 关键词：     

K/Cu(111)表面功函数的变化

本工作用俄歇电子能谱(AES)测定K在Cu(111)表面上的覆盖度,用Kelvin探头测量表面功函数的变化,得出功函数依赖于K覆盖度的关系曲线,功函数最大变化值△φ_max=3.14eV,功函数最小时的覆盖度θ_min=0.18,初始偶极矩p(0)=7.0Debye,实验结果与武汝前等人的理论模型相一致。 关键词：     

XPS-AES联用技术对Pt-Co，Cu-Au和Cu-Ag合金薄膜的定量表征方法研究

俄歇电子能谱(AES)在表面微区元素分析方面优势明显,但是受基体效应的影响,其定量分析,特别是非单质材料表面元素含量分析的准确度差,X射线光电子能谱(XPS)的定量分析准确度较高。为了降低AES定量分析的误差,将XPS和AES两种分析技术联用,选择Pt-Co,Cu-Au和Cu-Ag三种二元合金样品进行了研究,利用样品的XPS定量分析结果对AES的定量分析所用相对灵敏度因子进行修正,将修正后的相对灵敏度因子用于其他不同组分比的样品的定量分析,以验证其分析准确性。结果表明,修正后的灵敏度因子在用于AES定量分析时相对误差明显降低,分析相对误差小于10%。为了解决AES定量分析在积分谱处理形式下选峰困难的问题,将积分谱进行微分化处理,并修正了微分谱的处理形式下的相对灵敏度因子,AES的定量分析相对误差降低到小于9%,表明在两种处理形式下都能得到较为准确的定量结果。修正后的相对灵敏度因子包含了基体效应尤其是背散射效应的影响,从而有助于降低AES定量分析的误差。说明借助XPS提高AES定量分析准确度的研究方法具有一定的可行性。     

Bl结构MoNx薄膜的制备及物理性能研究

我们对以反应性溅射法制备的MoN_x薄膜测量了超导转变温度T_c,电阻率ρ(T)(从T_c起始到300K)。用X射线衍射技术、卢瑟福背散射(RBS)、俄歇谱仪和X射线光电子能谱(XPS)技术对这些样品进行了分析。实验结果表明T_c和ρ(T)随N含量改变而变化。当样品是B1结构时,T_c小于4.2K,而且样品内还有过量的N存在。俄歇分析表明,样品内有O,C杂质存在。这些因素都可能导致T_c很低,ρ(T)呈负的温度系数。 关键词：     

多层膜软X光反射镜的研制

本文介绍了镍-碳多层膜软X光反射镜的设计与制造方法,特别是膜厚监控法.用俄歇谱仪分析了一个样品的剖面情况;对一些样品在1.54(?)的衍射特性和在软X光区的反射率进行了测量并与理论计算结果作了比较.     

GexSi1-x/Si超晶格的俄歇深度剖面分析

用氩离子刻蚀和俄歇电子能谱测量Ge_xSi_1-x/Si应变层超晶格的成分深度分布,得到Ge,Si两种成分随深度的周期性变化,在二次电子象中观察到刻蚀坑边缘的明暗交替的周期性结构。讨论了用俄歇深度剖面分布作超晶格结构分析的特点及其局限性。 关键词：     

GaAs光电阴极制备工艺的俄歇分析

我们在一台制作第三代象增强器的超高真空系统中安装了俄歇(Auger)能谱仪,以其对GaAs光电阴极的制备过程进行在线监测分析,其中包括选择性腐蚀过程的俄歇观测,阴极激活前清洁措施的效果评价和Cs-O激活过程中As/Ga俄歇信号比对光电灵敏度的影响,Cs源纯度的分析及对光电发射的影响。根据分析结果,激活出了1000μA/lm的反射式光电阴极和500μA/lm的透射式光电阴极。     

三元合金Cu76Ni15Sn9的离子溅射研究

在２７ｋｅＶ Ａｒ⁺离子轰击时,用收集膜技术结合俄歇谱仪（ＡＥＳ）,研究了三元合金Cu₇₆Ni₁₅Sn₉系统的择优溅射行为。同时使用扫描电子显微镜（ＳＥＭ）与电子探针微分析（ＥＰＭＡ）．观察了靶点表面形貌变化并测定了形貌特征微区的合金组份原子的相对百分浓度。结果表明,Ｃｕ原子较Ｎｉ原子、Ｎｉ原子较Ｓｎ原子,在所测定范围（０─６０°）内择优发射。最后讨论了靶点表面形貌特征和“元素局域富集”现象对择优溅射过程的影响。 关键词：     

3d 金属电离损失谱研究

本文利用俄歇电子谱仪对Ti,Cr,Ni,Cu等3d金属的电离损失谱作研究,得到它们的空态密度的一些性质:空态密度的最大值位置、空态密度最大值的相对数值和空态密度的宽度。所得结果与理论模型一致。另外,从电离损失谱获得的束缚能值和自旋-轨道分裂值与用XPS所获结果符合良好。电离损失谱是一种研究空态密度的有效方法。 关键词：     

洞态氩离子的退激发及末电离态离子分布的理论研究

在描述洞原子(或离子)退激发过程只考虑单俄歇跃迁和辐射跃迁的辐射-单俄歇级联退激发模型的基础上,进一步考虑了双俄歇跃迁的贡献,发展了辐射-单俄歇-双俄歇级联退激发模型.据此模型研究了Ar⁺(1s^-1)(1s洞态氩离子)和Ar⁺(2s^-1)(2s洞态氩离子)的退激发过程及末电离态离子的分布,获得了与实验相符的结果. 关键词： 辐射-单俄歇级联退激发模型 双俄歇跃迁 辐射-单俄歇-双俄歇级联退激发模型 洞离子退激发     

高组份Al值的AlxGa1-x As和AlxGa1-x As/GaAs/AlxGa1-xAs/GaAs多层结构的MOCVD生长

用自制常压MOCVD系统,在半绝缘GaAs衬底上生长高Al组份Al_xGa_1-xAs（其x值达0.83）,和Al_xGa_1-xAs/GaAs/Al_xGa_1-xAs/GaAs多层结构,表面镜面光亮。生长层厚度从几十到十几μm可控,测试表明外延层晶格结构完整,x值调节范围宽,非有意掺杂低,高纯GaAs外延层载流子浓度n_300K=1.7×10¹⁵cm^-3,n_77K=1.4×10¹⁵cm^-3,迁移率μ_300K=5900cmcm²/V.S,μ_77K=55500cm²/V.S。用电子探针,俄歇能谱仪测不出非有意掺杂的杂质,各层间界面清晰平直。 对GaAs,AlGaAs生长层表面缺陷,衬底偏角生长温度及其它生长条件也进行了初步探讨。     

用肖特基电容电压特性数值模拟法确定调制掺杂AlxGa1-xN/GaN异质结中的极化电荷

研究发展了用肖特基电容电压特性数值模拟确定调制掺杂Al_xGa_1-xN/GaN异质结中极化电荷的方法.在调制掺杂的Al_0.22Ga_0.78N/GaN异质结上制备了Pt肖特基接触,并对其进行了C-V测量.采用三维费米模型对调制掺杂的Al_0.22Ga_0.78N/GaN异质结上肖特基接触的C-V特性进行了数值模拟,分析了改变样品参数对C-V特性的影响.利用改变极化电荷、n-AlGaN 关键词： xGa_1-xN/GaN异质结')" href="#">Al_xGa_1-xN/GaN异质结 极化电荷 电容电压特性 数值模拟     

AlxGa1-xP固溶体XPS和AES研究

采用XPS和AES对AI_xGa_1-xP(0≤x≤0.64)进行了研究。实验结果表明,组分比x增加时磷的2p结合能减小,价带顶退缩。同时鉴别和澄清了GaP微弱俄歇峰。 关键词：     

Photoluminescence and persistent photoconductivity of Al<Subscript>x</Subscript>Ga<Subscript>1-x</Subscript>N/GaN heterostructures

We have investigated the optical properties of Al_xGa_1-xN/GaN heterostructures (x=0.08, 0.15, 0.33) grown by metal organic chemical vapor deposition on sapphire using photoluminescence (PL) and persistent photoconductivity (PPC) measurements. For the Al_xGa_1-xN/GaN heterostructures (HS) containing high Al composition, we observed an anomalous temperature-dependent photoluminescence and persistent photoconductivity effects. These results show a strong dependence of the physical properties of Al_xGa_1-xN/GaN HS on the Al content and layer thickness. The anomalous temperature-dependent PL is usually attributed to the presence of carrier localization states. These phenomena are explained based on the alloy compositional fluctuations in the Al_xGa_1-xN/GaN HS. From the PPC measurements, the photocurrent (PC) quenching was observed for Al_xGa_1-xN/GaN HS and it is explained by the metastable states formed in the underlying GaN layer. Also, the mechanisms behind the PC quenching and PPC phenomena are explained in detail. PACS 72.20.Jv; 72.40.+w; 78.55.Cr     

An alternative approach to exciton binding energy in a GaAs-AlxGa1-x as quantum well

A variational-perturbative method is used to calculate the binding energy of an exciton in quantum well structure of Al_xGa_1-xAs-GaAs-Al_xGa_1-xAs. The fitness of potential well heights and differences of electron or hole effective mass in barrier region are both taken into considerations. The binding energies as a function of GaAs well sizes and as a function of alloy compositions, and a photon energy emitted in the recombination of an exciton, are presented. Validity of the calculation is discussed.     

Sacrificial etching of Al<Subscript>x</Subscript>Ga<Subscript>1-x</Subscript>As for III–V MEMS surface micromachining

A study of Al_xGa_1-xAs as a sacrificial film for surface micromachining is presented. Al_xGa_1-xAs etch rate and selectivity are measured over a range of aluminum mole fractions and HF etchant concentrations during the release of structural features up to 500 μm in width. The etch process is found to be diffusion limited, with an inverse power law relationship between etch depth and etch rate. Excellent selectivity greater than 10⁵ is achieved between sacrificial AlAs and structural GaAs, even for long etches up to 250 μm in length. Compared with previous studies of Al_xGa_1-xAs etching for epitaxial liftoff processing, measured etch rates for surface micromachining are approximately an order of magnitude lower, primarily due to the longer effective etch lengths required. However, unlike epitaxial liftoff, Al_xGa_1-xAs surface micromachining is compatible with higher HF concentrations which can provide comparable overall etch rates, with important implications for AlGaAs MEMS fabrication. PACS 81.05.Ea; 85.85.+j     

Effects of a cap layer on built-in electric fields of AlxGa1-xN/GaN heterostructures non-destructively probed by Franz-Keldysh oscillations

We have investigated electric field strengths in the Al_xGa_1-xN layer, F_AlGaN's, of Al_xGa_1-xN/GaN heterostructures with and without a GaN cap layer using photoreflectance (PR) spectroscopy. Franz-Keldysh oscillations (FKOs) from the Al_xGa_1-xN layer are clearly observed in the PR spectra. It is found from analysis of the FKOs that stacking of the cap layer causes a remarkable enhancement of F_AlGaN. This fact demonstrates that the FKO profile is a non-destructive probe for a change of built-in electric field strength induced by a cap layer. Numerical calculations of F_AlGaN based on a Schr?dinger-Poisson equation clarify that the magnitude of the enhancement of F_AlGaN is dominated by the cap-layer thickness.     

GaAs/AlxGa1-xAs量子阱红外探测器微结构研究

采用金属有机物化学气相沉积法生长了两种不同结构参数GaAs/AlxGa1-xAs量子阱材料。利用傅里叶光谱仪分别对势垒中Al组分为0.20,0.30的1#,2#样品进行77 K液氮温度下光谱响应测试。结果显示:1#,2#峰值响应波长为8.38,7.59 m,而根据薛定谔方程得到峰值波长为9.694,8.134 m,二者误差分别为13.6%,6.68%。针对误差过大及吸收峰向高能方向发生漂移的现象,利用高分辨透射扫描电镜对样品微观界面结构进行分析,结果显示,样品存在不同程度的位错及不均匀性。结果表明:位错引起AlGaAs与GaAs晶格不匹配,是造成1#误差较大的主要原因;峰值响应波长随势垒中Al组分的降低而增大,说明Al组分减小致使量子阱子带间距离缩小是导致峰值响应波长红移的原因。     

GaAs/AlxGa1-xAs超晶格子带间光跃迁的研究

运用Kronig-Penney模型的新形式,研究了超晶格子带间光跃迁的频率、带宽和跃迁强度,用GaAs/Al_xGa_1-xAs多量子阱材料做了关于红外吸收的实验,理论与实验符合较好。 关键词：     

New mechanism of surface polariton resonance at an isolated interface between transparent dielectric media (non-Tamm quasistationary surface polariton states)

A system of quantum dots on the basis of Al_xIn_1-xAs/Al_yGa_1-y As solid solutions has been studied. The usage of broadband Al_xIn_1-x solid solutions as the basis of quantum dots makes it possible to expand considerably the spectral emission range into the short-wave region, including the wavelength region near 770 nm being of interest for the design of aerospace systems of quantum cryptography. The optical characteristics of single Al_xIn_1-xAs quantum dots grown according to the Stranski–Krastanov mechanism are studied by the cryogenic microphotoluminescence method. The fine structure of exciton states of quantum dots is studied in the wavelength region near 770 nm. It is shown that the splitting of exciton states is comparable with the natural width of exciton lines, which is of great interest for the design of emitters of pairs of entangled photons on the basis of Al_xAs_1-x quantum dots.