镓掺杂碳纳米管场发射性能的研究

采用催化热解方法制备出镓掺杂碳纳米管,并利用丝网印刷工艺将其制备成纳米管薄膜.扫描电子显微镜观察表明,纳米管直径在20~50 nm之间.对此薄膜进行低场致电子发射测试表明,其场发射性能优于同样条件下未掺杂时的碳纳米管、碳氮纳米管和硼碳氮纳米管.当外加电场为1.1 V/μm,发射电流密度为50μA/cm2;当外电场增加到2.6 V/μm时,发射电子密度达到5 000μA/cm2.对其场发射机理进行探讨.     

氮气流量对氮化碳薄膜场致发射特性的影响

采用直流磁控溅射的方法,以镀Ti瓷片为衬底,改变N\-2和Ar的流量比,在衬底温度为400℃条件下制备了氮化碳薄膜,并对其场致发射特性进行研究,样品的开启电压为2.67V/μm,最大电流密度为17.31μA/cm2,比在同一系统制备的碳膜和用阴极电弧技术制备的氮化碳薄膜有更好的场发射特性.结果表明溅射气体中氮气含量对氮化碳薄膜的场发射特性有较大的影响.     

用机械破碎方法提高印刷碳纳米管薄膜的场发射性能

提出了一种可显著改善丝网印刷碳纳米管(CNTs)薄膜场发射特性的后处理方法,用机械压力通过隔离层对附着于CNTs表面的无机物进行原位破碎,并用高速气流清洁薄膜表面.同其他方法相比,机械破碎方法既不会在处理后的阴极表面留下残留物,也不会使薄膜受损.场发射特性测试表明,与未处理薄膜相比,经过处理的CNTs薄膜的开启场强从2.7V/μm降低到1.7V/μm,同样面积的薄膜(印刷面积为40mm×40mm)在4.2V/μm场强下的发射电流由70μA提高到了950μA,说明机械破碎处理对于提高薄膜的场发射特性有明显作用.该方法在碳纳米管场发射显示器的制作中具有很好的实际应用价值.     

低温淀积纳米非晶碳薄膜的场发射特性研究

以n型 ( 10 0 )Si为衬底 ,用CH4 和H2 作反应气体 ,在 150℃的衬底温度下淀积了非晶碳平面薄膜 .SEM照片和AFM均显示该薄膜具有很好的均匀性 ,非晶碳粒的尺寸为 90～ 10 0nm .喇曼谱分析表明 ,薄膜的主要成分为SP2 非晶碳 .对样品薄膜的不同区域进行了场发射特性的测试 ,各被测区域的场发射特性表现出很好的一致性 .在不同电压下进行了发光测试 .实验表明 ,样品薄膜的开启电场很低 ,约为 4V/ μm ,在 7V/ μm的电场下 ,场发射电流密度为 0 0 16A/cm2 ;用迭代法计算得薄膜的功函数为 0 65V .通过对样品的实际发射面积估算 ,得出发射点密度为 6× 10 4cm- 2 .     

氮气流量对氮化碳薄膜场到场致发射特性的影响

采用直流磁控溅射持方法，以镀Ti瓷片为衬底，改变N2和Ar的流量比，在衬底温度为400℃条件下制备了氮化碳薄膜，并对其场致发射特性进行了研究，样品的开启电压为 2．67V／μm，最大电流密度为17．31μA/cm^2，比在同一系统制备的碳膜和用阴极弧技术制备的氮化碳薄膜有更好的场发射特性。结果表明：溅射气体中氮气含量对氮化碳薄膜的场发射特性有较大的影响。     

金刚石聚晶薄膜制备及其电子场的发射性能

微波等离子体化学气相沉积是制备微/纳米结构的方法之一,使用该方法在陶瓷衬底上制备微米金刚石聚晶材料薄膜。利用扫描电子显微镜表征了材料的表面形貌,单元尺寸一致,分布均匀。使用X射线衍射和拉曼光谱分析了薄膜的结构,测试了薄膜材料的电子场发射性能。数据表明:制备的薄膜材料开启电场为1.25V/μm,在2.55V/μm的电场下,其电子场发射电流密度达到6.3mA/cm2。     

基底偏压对氮化硼薄膜场发射特性的影响

利用射频磁控溅射方法, 在n型（100）Si（0.008～0.02 Ω·m）基底上沉积了氮化 硼（BN）薄膜. 红外光谱分析表明, BN薄膜结构均为六角BN（h-BN）相. 在超高真空系统中 测量了BN薄膜的场发射特性, 发现BN薄膜的场发射特性与基底偏压关系很大, 阈值电场随基 底偏压的增加先增加后减小. 基底偏压为-140 V时BN薄膜样品场发射特性要好于其他样品, 阈值电场低于8 V/μm. F~N曲线表明, 在外加电场的作用下, 电子隧穿BN薄膜表面势垒发射 到真空.     

氮化硼薄膜的厚度对场发射特性的影响

利用射频磁控溅射方法, 在n型（100）Si基底上沉积了不同厚度（54~124 nm）的纳米氮化硼（BN）薄膜. 红外光谱分析表明, BN薄膜结构为六角BN（h-BN）相(1 380 cm^-1和780 cm^-1)结构. 在超高真空系统中测量了不 同膜厚的场发射特性, 发现阈值电压随着厚度的增加而增大. 厚度为54 nm的BN薄膜样品阈 值电场为10 V/μm, 当外加电场为23 V/μm时, 最高发射电流为240 μA/cm². BN薄膜场发射F-N曲线表明, 在外加电场作用下, 电子隧穿了BN薄膜表面势垒发射到真空.     

定向多壁碳纳米管薄膜及其场致发射距离敏感特性

研究了定向生长的多壁碳纳米管薄膜场致发射的距离敏感特性,以改进现有场发射传感器中硅及金属针尖的性能。化学气相沉积方法制备的多壁碳纳米管薄膜表现出良好的尖端放电特性,其开启电场可至1.42 V/μm,阈值电场可至2.22 V/μm,通过计算得到的尖端电场增强因子可至4 034以上。随着发射间距的增加,场致发射电流非线性地降低,发射电流对发射间距的最大变化率为0.018 8μA/μm。通过拟合分析发现,场致发射电流随发射间距的变化基本符合Fow ler-N ordhe im关系,该特性可作为碳纳米管场致发射传感器的基本原理用于位移的检测。     

基底温度对氮化硼薄膜场发射特性的影响

利用射频磁控溅射方法, 真空室中充入高纯N_{2(99.99%)和高纯Ar（99.99%）的混合气体, 在n型（100）Si基底上沉积了六角氮化硼（h-BN）薄膜. 在超高真空（<10^-7 Pa）系统中测量了BN薄膜的场发射特性, 发现 沉积时基底温度对BN薄膜的场发射特性有很大影响. 基底温度为500 ℃时沉积的BN薄膜样品场发射特性要好于其他薄膜, 阈值电场为12 V/μm, 电场升到34 V/μm, 场发射电流为280 μA/cm². 所有样品的Fowler-Nordheim(F-N)曲线均近似为直线, 表明电子是通过 隧道效应穿透BN薄膜发射到真空的.}     

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.     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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