Si_（83）Ge_（17）/Si压应变衬底上HfAlO_x栅介质薄膜微结构、界面反应和介电性能研究

本文研究了射频磁控溅射沉积在p-Si83Ge17/Si（100）压应变衬底上HfAlOx栅介质薄膜的微结构及其界面反应,表征了其各项电学性能,并与相同制备条件下沉积在p-Si（100）衬底上薄膜的电学性能进行了对比研究.高分辨透射电子显微镜观测与X射线光电子能谱深度剖析表明600°C高温退火处理后,HfAlOx薄膜仍保持非晶态,但HfOx纳米微粒从薄膜中分离析出,并与扩散进入膜内的Ge,Si原子发生界面反应生成了富含Ge原子的HfSiOx和HfSix的混合界面层.相比在相同制备条件下沉积在Si（100）衬底上的薄膜样品,Si83Ge17/Si（100）衬底上薄膜的电学性能大幅提高：薄膜累积态电容增加,有效介电常数增大（～17.1）,平带电压减小,？1V栅电压下漏电流密度J减小至1.96×10？5A/cm2,但电容-电压滞后回线有所增大.Si83Ge17应变层抑制了低介电常数SiO2界面层的形成,从而改善了薄膜大部分电学性能;但混合界面层中的缺陷导致薄膜界面捕获电荷有所增加.     

硅基超晶格Ⅵ(A)/Si6/SiO2/Si6/Ⅵ(A)的电子结构

硅的有效光发射是硅基光电器件研究的一个关键问题,因此一直受到广泛的关注.本文采用第一性原理对新的硅基材料Ⅵ(A)/Sim/SiO2/Sim/Ⅵ(A)(m=6,Ⅵ(A)=O,Se)的能带结构、态密度和电荷密度等进行了计算研究.通过改变掺入Ⅵ(A)族原子氧和硒的对比,分析了SiO2层、不同的Ⅵ(A)族原子以及它们与最近邻Si原子的相互作用对硅基材料电子性质的影响.研究表明,在局域密度近似(LDA)下,O/Si6/SiO2/Si6/O结构在X点存在准直接带隙的特征,而Se/Si6/SiO2/Si6/Se在Γ点存在很小的直接带隙.     

一种计算纳米CMOS器件中应力致界面态的方法

在纳米CMOS器件中,负栅压温度不稳定性、热载流子注入效应和栅氧化层经时击穿等应力使得Si/SiO2界面产生界面态,引起器件参数的退化.随着CMOS器件不断缩小,这种退化将严重制约器件性能.提出了一种改进的计算纳米CMOS器件中应力产生界面态的方法,能够对应力产生的界面态进行定量描述.该方法在电荷泵基础上测量纳米小尺寸器件初始状态和应力状态下的衬底电流,提取电荷泵电流(Icp),计算出应力产生的界面态密度.测量过程中,脉冲频率固定不变,降低了频率变化所带来的误差.     

具有纳米质点性质的MFI型硅沸石微细晶粒的合成及表征(英)

分别以白炭黑（Ⅰ）和硅溶胶（Ⅱ）为硅源，在（TPA）2O－Na2O－SiO2－H2O体系（TPA为四丙基铵）中，反应温度为60℃，合成了高结晶度纯硅沸石．用扫描电子显微镜（SEM）法测得的晶粒大小分别为0．20μm（Ⅰ）和0．45μm（Ⅱ）；用粉末X射线衍射（XRD）线宽法测得的晶粒大小为0．02μm．与高温（180℃）合成的硅沸石样品相比较，低温合成的微细晶粒硅沸石样品已具备纳米级材料的若干特性．微细晶粒硅沸石的正己烷吸附量和比表面都非常大．XRD谱，红外吸收光谱（FT－IR），29Si魔角固体核磁共振（29SiMASNMR）和热重分析（TG／DTG／DTA）的研究证明，微细晶粒硅沸石的结构破坏温度和单斜／正交对称性相转变温度明显地比高温合成的硅沸石低，硅羟基缺陷也明显地增加．0．20～0．45μm的微细晶粒硅沸石的比表面几乎与胶体质点相同，它的外表面积达100m2／g，中孔容积为0．10～0．12ml／g，平均孔径为2．6～2．7nm．这表明微细晶粒硅沸石实际上是纳米质点的结合体．     

以SiO2/Si为衬底的Ba1-xLaxNbyTi1-yO3薄膜的敏感特性

通过离子束溅射技术淀积在SiO2/Si衬底上的钛酸镧钡铌膜（Ba1-xLaxNbyTi1-yO3），制成集薄膜电阻和金属－绝缘体－半导体（MIS）电容为一体的传感器。实验结果表明，薄膜电阻在303－673K温度范围内对可见光和热具有良好的灵敏特性，同时MIS电容对相对湿度有很高的灵敏度。我们测试了此薄膜的光吸收特性，并得到了它的禁带宽度。最后，我们研究了薄膜电阻的阻抗温度频率特性和频率对MIS电容湿敏特性的影响。     

Cu2S阻性存储薄膜的制备及开关特性研究

采用脉冲激光沉积（PLD）方法于室温下在Pt/TiO2/SiO2/Si（111）及高导电的Si（111）衬底上制备了Cu2S固体电解质薄膜,后经X-射线衍射、原子力显微技术对薄膜的晶体结构和表面形貌进行了表征.通过400℃退火的Cu2S薄膜在Pt/TiO2/SiO2/Si（111）衬底上取向生长,而在高导电性Si（111）衬底上则无取向生长.最好用聚焦离子束刻蚀技术及PLD方法制备了Cu/Cu2S/Pt及Cu/Cu2S/Si（111）记忆单元,这些记忆单元都显示了较好的电阻开关特性,但是在不同衬底上制备的记忆元的＂关态＂与＂开态＂的电阻比表现出较大的差异,这些差异被归结为非反应电极与Cu2S薄膜间的不同界面性质所致.     

纳米二氧化硅粒子在水性聚氨酯中分散性的研究

采用六甲基二硅胺烷(HMDS)对气相二氧化硅和硅溶胶中两种纳米二氧化硅（SiO2）粒子表面进行了化学接枝改性,然后将改性后的纳米SiO2粒子加入到水性聚氨酯(WPU)中,制备了一系列不同纳米SiO2粒子含量的共混改性WPU样品.通过FT-IR,SEM对纳米SiO2粒子共混改性WPU成膜物的织态结构进行了表征,并研究了SiO2/WPU共混乳液的成膜过程对成膜物织态结构的影响.结果表明,纳米SiO2粒子表面改性状态很大程度上决定了纳米SiO2粒子在共混成膜物中的分散状态和织态结构,具有一定表面两亲性的纳米Si     

激光再结晶多晶硅/二氧化硅界面性质的测定

我们用常规的高频和准静态C-V技术测量了氩离子激光再结晶多晶硅/二氧化硅界面的氧化物固定电荷密度N_f和界面态陷阱密度N_(it)。结果表明,和未再结晶的热退火样品相比,激光再结晶后,背界面的界面态密度大幅度下降。该界面态性质还与二氧化硅的生长方法和条件有关。在硅单晶抛光片上用氯化氢氧化法或三氯乙烯氧化法热生长约1400A的SiO_2层,然后用低压化学气相淀积法淀积约5000A多晶硅薄膜。使用氩离子激光器连续扫描辐照样品,功率选用4.5W、扫描速度2cm/s、束斑直径40μm,交叠50％,衬底温度300℃—400℃。经激光再结晶后多晶硅薄膜的晶粒由原来的100A长大到数微米。     

P型杂质Ga在SiO2—Si内界面分凝规律研究

采用开管方式和SiO2/Si系统,实现了P型杂质Ga在硅中的可控制掺杂。借助二次离子质谱（SIMS）和扩展电阻（SRP）分析方法,对已掺Gar 杂质硅,在二次氧化过程中产生的分凝效应进行了系统研究,首次得出Ga分凝的规律性,导出了Ga在SiO2-Si内界面Si一侧最低浓度值随时间变化的表达式。为全面理解Ga的扩散特性和建立开管扩Ga模型奠定了基础。     

激光烧蚀制备纳米Si晶粒的激光能量密度阈值

在10 Pa的Ar环境气氛下,采用脉冲激光烧蚀方法在玻璃或单晶Si(111)衬底上制备了纳米Si晶薄膜. 为了确定能够形成纳米Si晶粒的激光能量密度阈值,在0.40～1.05 J/cm2内实验研究了激光能量密度对纳米Si晶粒形成的影响. 扫描电子显微镜(SEM)测量证实,随着激光能量密度的减小,所形成的纳米Si晶粒数目逐渐减少. 当激光能量密度低于0.43 J/cm2时,衬底表面不再有纳米Si晶粒形成. 从激光烧蚀动力学角度出发,对实验结果进行了定性分析.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that