退火对ZrO2薄膜微结构及激光损伤阈值的影响

利用电子束蒸发方法在Yb:YAG晶体和熔融石英衬底上沉积单层ZrO2薄膜,分别在673 K和1 073 K的温度下经过12 h退火以后,通过X射线衍射(XRD)分析了薄膜晶相,计算了薄膜的晶粒尺寸;利用表面热透镜技术获得了薄膜的吸收;测量了退火后薄膜的激光损伤阈值.实验结果表明:两种衬底上的薄膜结构受到退火温度和衬底表面结构的影响,高温退火有利于单斜相的形成,含单斜相的ZrO2薄膜具有较高的激光损伤阈值,而由于衬底的吸收,Yb:YAG晶体上薄膜的损伤阈值远小于石英衬底上薄膜的损伤阈值.

Ta2O5膜在532, 800 和 1064 nm波长的n-on-1体系下的激光损伤阈值研究

Ta2O5膜采用传统的电子束蒸发方法制备，并在氧气中673 K的条件下进行了退火12 h处理。首先在1-on-1体系下对Ta2O5膜进行了532和1064 nm波长下的激光损伤阈值（LIDT） 研究，然后在n-on-1体系下分别对532，800和1064 nm三种波长下的激光损伤阈值进行了研究。结果表明在n-on-1体系下Ta2O5膜在532和1064 nm波长下的阈值均高于1-on-1体系下的阈值。此外，在n-on-1体系下，薄膜的阈值随波长增加而增大。同时发现，在氧气中进行退火对Ta2O5膜的光学性能

基于错配修复系统的基因突变检测生物芯片研究

许多人类疾病和微生物抗药性的产生都是由基因组中单个碱基的替换、插入或缺失等基因突变引起的。因此，迫切需要发展快速、高通量基因突变检测方法来实现对基因疾病和细菌抗药性的早期诊断。本研究针对匕述需求发展了纂于DN八错配修复系统的墓因突变检测生物芯片方法。根据DNA错配修复MtltS蛋白结构与功能上的高度保守性，通过PCR从E.coli K-12基因组中扩一增出DNA错配修复基因，甩石（2.56kb）。通过基因水平的分子操纵，构建了Trx-His6-MutS（THM）、Trx-His6-Linker peptide-Muts（THLM）、Trx-His6-GFP-Linker peptide-MutS（THGLM）和Trx-His6-Linker peptide-Strep-tagll-Linker peptide-MutS（THLSLM）的融合基因并在大肠杆菌中进行了IPTG诱导表达。SDS-PAGE分析表明均有一与预期分子量相应的诱导表达条带出现，其表达量占菌体蛋白的30％左右，且以可溶形式存在。融合蛋白中Trx和His6亲和肤能增加表达蛋白的可溶性及便于蛋白的纯化。连接肤的加入增大了融合蛋白各个成分之间的距离，减少空间位阻，使各个蛋白能够较大程度地保持其原有的生物活性。MLltS融合蛋白的生物活性鉴定结果表明：它们既能识别、结合含有错配碱基的DNA双链，又保留了其它融合成分的生物活性。利用融合蛋白THLSLM中的Strep-tagII与Streptavidin相互作用的天然特性，使融合蛋白THLSLM在StrePtavidin修饰过的芯片基质上自动布阵沉积，制作成蛋白质芯片来识别、结合样品中含有错配或未配刘碱基的DNA双链。THGLM、THLM-Cy3和THLSLM能够使MutS蛋白显示不同的标记信号，通过它们识别并结合固定在DNA芯片基质上的基因片段来发展基因突变检测DNA芯片方法。利用基于MutS的蛋白质芯片和DNA芯片方法对含有不同错配类型、不同长度的DNA片段和错配序列背景对错配结合的影响做了深入研究，证明了MutS介导的基因突变检测生物芯片方法的可行性。基于MutS蛋白的鳌因突变检测生物芯片方法借用了生物系统本身的DNA错配修复（Mismatch Repair，MMR）机制。DNA错配修复过程是许多修复蛋白之间的相互作用共同完成的，其中蛋白MutS、MutL和MutH在肠道细菌例如大肠杆菌的甲基定向错配修复中起决定作用。这些修复蛋白的相关研究也引起了越来越多学者的关注，但对于MutL蛋白的体外生物功能一直存在争议，从而限制了该蛋白的应用研究。本研究利用基因的体外拼接技术构建了融合蛋白Trx-Hi56-Linker peptide-MutL（THLL）、Trx-His6-GFP-Linker peptide-MutL（THGLL）和Trx-His6-Linker peptide-Strep-tagII-Linker peptide-MutL（THLSLL）。非变性凝胶电泳鉴定MutL融合蛋白体外生物功能结果表明：THLL、THGLL和THLsLL都能增加融合蛋白Trx-His6-Linker peptide-MutS（THLM）与含有错配碱基DNA双链的结合，但受ATP浓度变化的影响很大。通过融合蛋白THGLL中绿色荧光蛋白（Green Fluorescent Protein，GFP）的荧光信号或THLSLL中Strep-tagII的特性并利用酶学反应来指示该蛋白的存在，发展了体外研究DNA错配修复蛋白MtuS和MutL之间相互作用的简便方法。本研究以构建的MutS融合蛋白为分子识别元件发展了基因突变检测生物芯片并利用构建的MutL融合蛋白发展了体外研究DNA错配修复蛋白MLuS和MutL之间相互作用的简便方法。建立的融合分子系统方法也为研究其它的蛋白质或生物大分子之间的相互作用提供了一个技术平台。此外，本研究构建的融合蛋白THGLL及其 DNA错配修复蛋白与GFP的融合构想还可用来进行DNA错配修复基因产物的表达与基因突变频率和人类肿瘤恶性程度的相关性研究。

Effects of solution viscosity on heterogeneous electron transfer across a liquid/liquid interface

Scanning electrochemical microscopy (SECM) is employed to investigate the effect of solution viscosity on the rate constants of electron transfer (ET) reaction between potassium ferricyanide in water and 7,7,8,8-tetracyanoquinodimethane (TCNQ) in 1,2-dichloroethane. Either tetrabutylammonium (TBA(+)) or ClO4- is chosen as the common ion in both phases to control the interfacial potential drop. The rate constant of heterogeneous ET reaction between TCNQ and ferrocyanide produced in-situ, k(12), is evaluated by SECM and is inversely proportional to the viscosity of the aqueous solution and directly proportional to the diffusion coefficient of K4Fe(CN)(6) in water when the concentration of TCNQ in the DCE phase is in excess. The k(12) dependence on viscosity is explained in terms of the longitudinal relaxation time of the solution. The rate constant of the heterogeneous ET reaction between TCNQ and ferricyanide, k(21), is also obtained by SECM and these results cannot be explained by the same manner.

Photoluminescent multilayer films based on polyoxometalates

Ultrathin multilayer films consisting of the polyoxotungstoeuropate cluster K-12[EuP5W30O110] (EuP5W30) and poly( allylamine hydrochloride) (PAH) have been prepared by the layer-by-layer self-assembly method. The (EuP5W30 /PAH) multilayer films have been characterized by small-angle X-ray reflectivity measurements, X-ray photoelectron spectra, and atomic force microscopy (AFM). From the AFM images, the thickness of the {PEI/PSS/PAH(EuW30/PAH)} multilayer film was estimated to be 6.5 nm, corresponding to an average thickness of ca. 1.1 nm for a EuW30/PAH layer pair. The photoluminescent behavior of the film at room temperature was investigated to show the characteristic Eu3+ emission pattern of D-5(0)-->F-7(J). The fluorescence behavior of the multilayer film is essentially identical to that of H-n[EuP5W30O110]((12-n)-) in a concentrated aqueous solution, except for the relative intensities and peak bandwidths. The occurence of photoluminescent activity confirms the potential for creating luminescent multilayers with polyoxometalates (see ref. 23).

84.5MeV~(12)C~(4+)离子诱发金属靶原子发射的Kβ与Kα-X射线强度比值的研究

本实验是在中国科学院兰州近代物理研究所,国家实验室的重离子加速器上完成的.实验用OR-TEC公司生产的HPGe X射线探测器测量了84.5 MeV的12C4+离子轰击Cu,Mo,Ag,Cd,In,Sn,W和Au金属靶产生的K壳层特征X射线谱,计算了Kβ与Kα-X射线强度的比值,并将结果与Scofield用Hartree-Fock-Slater模型计算出的理论值与用其它方法(如:衰变幅射,用光子,电子,质子等粒子与靶相互作用)得到的实验值进行了比较.比较结果表明用84.5 MeV的12C4+离子轰击Cu,Mo,Ag,Cd,In,Sn,W和Au金属靶产生的Kβ与K-αX射线强度比值比理论值和其它实验值要大许多.

Role of interface dipole in metal gate/high-k effective work function modulation by aluminum incorporation

The interface dipole and its role in the effective work function (EWF) modulation by Al incorporation are investigated. Our study shows that the interface dipole located at the high-k/SiO2 interface causes an electrostatic potential difference across the metal/high-k interface, which significantly shifts the band alignment between the metal and high-k, consequently modulating the EWF. The electrochemical potential equalization and electrostatic potential methods are used to evaluate the interface dipole and its contribution. The calculated EWF modulation agrees with experimental data and can provide insight to the control of EWF in future pMOS technology.

THIN-FILM BIPBSRCACUO DIRECT-CURRENT SUPERCONDUCTING QUANTUM INTERFERING DEVICES OPERATING AT 78-K

Direct current SQUIDs (superconducting quantum interference devices) have been successfully fabricated by using a Pb-doped BiSrCaCuO superconducting thin film made by mixed evaporation of a single source composed of related components with a resistance heater. The dc SQUID comprises a square washer with a small hole. These SQUIDs show perfectly periodic voltage-flux characteristics without magnetic shield, that is, typically, the flux noise and energy resolution at a frequency range from dc to 1 Hz and at 78 K being 1.7 x 10(-3) PHI-0/ square-root Hz and 3.6 x 10(-26) J/Hz, respectively. Meanwhile, we have found out that one of the SQUIDs still was able to operate on flux-locked mode without bias currents and showed voltage-flux second harmonic characteristics. This phenomenon is not well understood, but it may be related to I-V (current-voltage) characteristics of the dc SQUID.

Low-temperature (10 K) infrared measurement of interstitial oxygen in heavily antimony-doped silicon via wafer thinning

A new technique is reported for the rapid determination of interstitial oxygen in heavily Sb-doped silicon. This technique includes wafer thinning and low-temperature 10 K infrared measurement on highly thinned wafers. The fine structure of the interstitial oxygen absorption band around 1136 cm(-1) is obtained. Our results show that this method efficiently reduces free-carrier absorption interference, allowing a high reliability of measurement, and can be used at resistivities down to 1 x 10(-2) Omega cm for heavily Sb-doped silicon.

VLSI architecture of a K-best detector for MIMO--OFDM wireless communication systems

The K-best detector is considered as a promising technique in the MIMO-OFDM detection because of its good performance and low complexity. In this paper, a new K-best VLSI architecture is presented. In the proposed architecture, the metric computation units (MCUs) expand each surviving path only to its partial branches, based on the novel expansion scheme, which can predetermine the branches' ascending order by their local distances. Then a distributed sorter sorts out the new K surviving paths from the expanded branches in pipelines. Compared to the conventional K-best scheme, the proposed architecture can approximately reduce fundamental operations by 50% and 75% for the 16-QAM and the 64-QAM cases, respectively, and, consequently, lower the demand on the hardware resource significantly. Simulation results prove that the proposed architecture can achieve a performance very similar to conventional K-best detectors. Hence, it is an efficient solution to the K-best detector's VLSI implementation for high-throughput MIMO-OFDM systems.

截止波长12μm的InAs0.04Sb0.96/GaAs的熔体外延生长及特性研究

用熔体外延(ME)法在半绝缘(100)GaAs衬底上成功生长出了截止波长为12 μm的InAs0.04Sb0.96外延层.傅立叶变换红外(FTIR)透射光谱揭示,InAsSb合金的禁带宽度被强烈变窄.通过分析InAs0.04Sb0.96外延层载流子浓度的温度依存性表明,其室温禁带宽度为0.105 5 eV,与透射光谱测得的数值很好地一致.通过测量12～300 K的吸收光谱,研究了InAs0.04Sb0.96/GaAs的禁带宽度的温度依存性.霍尔测量得出300 K下样品的电子迁移率为4.47×104 cm2/Vs,载流子浓度为8.77×1015 cm-3;77 K下电子迁移率为2.15×104 cm2/Vs,载流子浓度为1.57×1015 cm-3;245 K下的峰值迁移率为4.80×104 cm2/Vs.

Origin of flat-band voltage sharp roll-off in metal gate/high-k/ultrathin- SiO2/Si p-channel metal-oxide-semiconductor stacks

The origin of the flat band voltage roll-off (V-FB roll-off) in metal gate/high-k/ultrathin-SiO2/Si metal-oxide-semiconductor stacks is analyzed and a model describing the role of the dipoles at the SiO2/Si interface on the V-FB sharp roll-off is proposed. The V-FB sharp roll-off appears when the thickness of the SiO2 interlayer diminishes to below the oxygen diffusion depth. The results derived using our model agree well with experimental data and provide insights to the mechanism of the V-FB sharp roll-off.

Fermi-Level Pinning at Metal/High-k Interface Influenced by Electron State Density of Metal Gate

The Fermi-level pinning (FLP) at the metal/high-k interface and its dependence on the electron state density of the metal gate are investigated. It is found that the FLP is largely determined by the distortion of the vacuum level of the metal which is quantitatively ruled by the electron state density of the metal. The physical origin of the vacuum level distortion of the metal is attributed to an image charge of the interface charge in the metal. Such results indicate that the effective work function of the metal/high-k stack is also governed by the electron state density of the metal.

空心原子的K-x射线谱

报道了利用兰州重离子加速器国家实验室ECR离子源首次引出的全裸Ar离子和类氢、类氦、类锂Ar离子与Be固体表面相互作用形成的空心原子x射线实验测量结果 .结果发现 ,同样条件下 ,由于K壳层电子的剥离 ,Ar的K_x射线单离子发射产额增加了 5个量级 ,约为 3 6× 10 - 3每原子 ;而当L壳层存在电子时 ,Ar的K_x射线几乎观测不到