腔室长时间使用造成的工艺漂移对微晶硅薄膜性质的影响

考查了等离子体增强化学气相沉积(PECVD)高压制备微晶硅(μc-Si:H)薄膜过程中,系统长时间使用造成的微晶硅薄膜特性的漂移情况。实验中,控制沉积条件,使薄膜的沉积速率达到约0.5nm/s;保证硅薄膜具有一定的晶化程度(40%～80%),由不同探测波长的Raman散射谱估算纵向结构变化。以腔室使用时间作为基准,考查不同硅烷浓度下制备的样品,发现在相同沉积条件下,材料的晶化率和光暗电导随腔室使用时间的增加而不断增大,沉积速率随之大幅提高。观察发现,在电极板和腔室壁上积累了大量硅反应残留物(硅粉末和硅薄膜),分析认为,薄膜特性漂移是这些硅残留物不断参与等离子体及成膜反应的结果。研究表明,提高硅烷浓度可有效校正微晶硅薄膜电学及结构特性的漂移,同时保持高速沉积。     

甚高频对微晶硅薄膜微观结构的影响

系统研究了射频和甚高频下沉积微晶硅薄膜时沉积参数对薄膜质量的影响,并优化了沉积参数．在相同的沉积条件下,甚高频沉积速度明显大于射频沉积速度,并且制备出的太阳能电池效率同样高于射频沉积．一般情况下,当沉积速率提高时,沉积薄膜中存在大量悬挂键和Si-2H键等缺陷,会大大降低材料的光电性能,同样也会降低太阳能电池的效率．在保证材料的光电性能的前提下提高沉积速度,沉积参数需要优化．在系列优化沉积参数后,微晶硅沉积速率达到0．75nm／s,在该沉积速率下,制备出的单结n—i—P结构的太阳能电池效率达到5．41％．     

射频功率对反应磁控溅射法沉积的a-C:F薄膜的影响

以高纯石墨作靶、CHF3／Ar作源气体，采用反应磁控溅射沉积法制备了具有低介电常数(k～2．18)的氟化非晶碳(a—C：F)薄膜．薄膜的结构和性质由红外吸收光谱、紫外可见光光谱、沉积速率及介电常数等作了表征，有关数据显示，薄膜的沉积速率随着射粒输入功率的增大而上升，所沉积的a—C：F薄膜中存在着一定比例的苯环结构，改变射频功率可以改变薄膜中的F／C比值，调制薄膜中环式结构与链式结构的比例，从而影响薄膜的介电常数和光学带隙等性能。     

PECVD法低温制备微晶硅薄膜的晶化控制

采用等离子体增强化学气相沉积(PECVD)法在玻璃衬底上低温制备了微晶硅(μc-Si:H)薄膜。利用拉曼(Raman)散射谱、原子力显微镜(AFM)研究了H2稀释、衬底温度、射频功率等对薄膜晶化的影响。研究结果表明,当H2稀释比从95%升高到99%、衬底温度从200℃逐渐升高到400℃、硅膜的晶化率逐渐提高,结构逐渐由非晶向微晶转变,射频功率对薄膜晶化的影响有一最优值。     

利用射频PECVD技术低温制备纳米晶硅薄膜

利用射频等离子体增强化学气相沉积(PECVD)技术低温制备了氢化纳米晶硅(nc-Si:H)薄膜.通过优化沉积参数,得到晶粒尺度小于10 nm,晶态体积比为58%的nc-Si:H薄膜.对nc-Si:H薄膜的光电特性进行研究,结果表明,在100 mW/cm2的光照下,nc-Si:H薄膜的光电导率为1.5×10-3Ω-1.cm-1,室温暗电导率为8.4×10-4Ω-1.cm-1,光学带隙为1.46 eV.利用射频PECVD制备的nc-Si:H薄膜具有明显的量子点特征.     

氢化微晶硅薄膜沉积的气相反应过程模拟

以SiH4和H2为反应气源,建立了等离子体增强化学气相沉积法制备氢化微晶硅(μc-Si:H)薄膜的气相反应模型,模拟了硅烷浓度、等离子体参数(如电子温度Te和电子密度ne)等对气相反应的影响.结果表明:SiH3是μc-Si:H薄膜的主要沉积前驱物;随着硅烷浓度增大,等离子体中SiH3等前驱物的浓度增大,而H原子的浓度快速下降,二者的浓度比(H/SiH3)随之降低;随着Te和ne的增大,H原子的浓度单调升高,SiH3等前驱物的浓度先增大然后趋于饱和,H/SiH3比值增大.     

射频功率和沉积气压对非晶硅薄膜材料性能的影响

采用等离子体增强化学气相沉积技术,通过改变射频功率与沉积气压两个参数来沉积非晶硅薄膜材料,并研究了变化参数对薄膜沉积速率、晶化情况、氢含量、光电学性质以及材料表面形貌等的影响.结果表明:射频功率在较低的范围内变化时,对薄膜的沉积速度影响很大,对材料的光电特性比较敏感;沉积气压升高达到一定值后,沉积速率变化不太明显,光电影响比较缓和;在低气压、小功率条件下,薄膜中出现小晶粒生长.     

氮化硅镀膜工艺参数优化

利用等离子体增强化学气相沉积(PECVD)法沉积给定折射率的氮化硅薄膜,通过正交实验法对衬底温度、NH_3流量和射频功率3个对氮化硅薄膜沉积速率影响较大的工艺参数进行全局优化和调整,得到了氮化硅镀膜的最优工艺参数。     

射频磁控溅射沉积SiO2膜的研究

研究以射频磁控溅射法在Ｓｉ衬底上沉积ＳｉＯ２膜．这一方法避免了高温氧化法对器件性能的损害．在结构和物理性能上对ＳｉＯ２进行了多方面的测试和分析．结果表明，ＳｉＯ２膜具有：１）微晶结构，结构致密、表面均匀、无针孔等．２）优良的物理性能，腐蚀速率（在Ｐ腐蚀液中）０．２０～０．２４ｎｍ／ｓ，击穿场强２．６×１０７～４．４×１０７Ｖ／ｃｍ．可以得出结论：射频磁控溅射法沉积的ＳｉＯ２膜与热氧化法沉积的ＳｉＯ２膜具有相同的物理性质．     

微波等离子体CVD方法制备金刚石薄膜

采用微波等离子体化学气相沉积方法分别在CH4／H2，CO／H2和（CH4＋CO）／H2气体体系下合成了金刚石薄膜．结果表明，所合成的金刚石薄膜具有明显的柱状生长特性和较高的品质，（CH4＋CO）／H2体系合成的金刚石薄膜具有较高的生长速率和（100）晶面定向生长的特性．     

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