MOVPE生长1.55μm InGaAsP材料和InGaAsP/InP量子阱

报导了LP-MOVPE InGaAsP/InP体材料和量子阱的生长.生长的与InP匹配的1.55μm波长的InGaAsP材料,在77K时光荧光半峰宽达18.7meV,InGaAsP/InP量子阱的半峰宽为18.0meV.     

GaInP/(Al_xGa_(1-x))InP多量子阱结构的光荧光特性分析

利用金属有机化合物气相沉积(MOCVD)技术生长了GaInP/(AlxGa1-x)InP多量子阱(MQW)结构材料,对其进行光荧光特性测量,观察到在波长λ=647 8nm和λ=861 6nm处分别存在一个强发光锋和一个弱发光峰.理论计算和实测结果基本一致.     

InP/InGaAsP/InP多量子阱太阳电池结构的优化研究

用金属纳米粒子沉积在InP/InGaAsP/InP多量子阱太阳电池表面,利用光散射来研究该电池改善后的光电性能。金属纳米粒子对量子阱太阳电池器件光电性能的作用结果是：用量子阱层与周围材料反射系数的差异来限制不同方向的入射光进入太阳电池器件侧面的传播路径。量子阱太阳电池通过这种结构优化设计,对于硅和 Au 纳米粒子,可以观察到短路电流密度分别增加了12.9%和7.3%,输出最大功率的转换效率分别增加了17%和1%。     

基于电子自旋弛豫的全光开关的理论计算

国外已有实验测量发现，InGaAsP多量子阱材料的电子自旋弛豫时间是与材料的阱宽大小直接联系的，而且比之前研究的GaAs多量子阱材料的自旋弛豫时间更短。文中对激子的特性进行了介绍，对影响电子自旋弛豫时间的三个机制经行了分析和计算，并且采用有限深势阱摸型对InGaAsP多量子阱的组分和阱宽之间的关系进行了计算，最后根据要制作的全光功能开关的性能指标对计算结果进行了选择，得到最适合于制作光开关的材料为：势阱In0．53Ga0．47As（阱宽6nm）；势垒InP。     

准对称耦合量子阱与光开关结构优化设计

根据光开关对量子阱材料的要求,提出了具体的量子阱结构优化原则。以准对称耦合量子阱为蓝本,利用此优化原则,对其结构进行优化。通过对优化后的准对称耦合量子阱电光特性的分析,发现该量子阱结构在低工作电压(F=40 kV/cm)、低吸收系数(α<100 cm-1)的情况下仍有一很大的场致折射率变化(对TE模入射光,(Δn)max=0.021 6;对TM模入射光,(Δn)max=0.033),从而验证了优化程序的正确性。     

GaInP/ ( AlxGa1- x ) InP 多量子阱结构的光荧光特性分析

利用金属有机化合物气相沉积(MOCVD)技术生长了GaInP／(AlxGa1-x)InP多量子阱(MQW)结构材料，对其进行光荧光特性测量，观察到在波长λ=647．8mm和λ=861．6nm处分别存在一个强发光锋和一个弱发光峰．理论计算和实测结果基本一致．     

施加电场的单量子阱中束缚态的能级

超晶格由2种不同晶体材料交替生长的具有周期性结构的多层薄膜构成,2种材料的势垒-势阱结构就是量子阱.通过理想的无限深势阱模型,讨论了施加电场作用的超晶格中单量子阱束缚态的能级结构和态密度,得到了体系的本征能量与本征函数.分析表明:沿超晶格生长方向能量量子化,量子化能量构成了一系列子能带(微带);在电场作用下,超晶格量子阱能级向低能方向移动,施加电场不影响超晶格量子阱子能带的电子态密度.     

掩埋隧道结的研制及其在1.3μm VCSEL结构中的应用

采用气态源分子束外延（GSMBE）技术在（100）InP衬底上分别了生长了δ掺杂的P^＋ -AllnAs—n^＋ -InP和P^＋ -InP—n^＋ -InP两种隧道结结构,用电化学C—V和I—V特性曲线表征了载流子浓度和电学特性,发现P^＋ -AllnAs-n^＋ -InP隧道结性能好于P^＋ -InP-n^＋ -InP隧道结。接着在（100）InP衬底上生长了包含P^＋ -AllnAs-n^＋ -InP掩埋隧道结和多量子阱有源层的1．3μm垂直腔面发射激光器（VCSEL）结构,测试得出其开启电压比普通的PIN结VCSEL小,室温下其电致荧光谱波长在1．29μm。     

纤锌矿GaN/AlN量子阱中的极化子

采用Lee-Low-Pines(LLP)变分法,讨论了纤锌矿(闪锌矿)GaN/AlN无限深量子阱材料中电子-定域长波光学声子相互作用,给出纤锌矿量子阱中自由极化子的基态能量、第一激发态能量和跃迁能量随阱宽的变化关系.数值计算中考虑了纤锌矿材料的各向异性,结果表明,极化子能量随阱宽的增大而减小,当阱宽较宽时,趋近于体材料的三维值.纤锌矿(闪锌矿)GaN/AlN量子阱材料中,电子-定域长波光学声子相互作用对极化子能量的贡献比闪锌矿GaAs/AlAs量子阱材料中的相应值大得多.因此,讨论GaN/AlN量子阱材料中电子态问题时应考虑电子-定域声子相互作用.     

基于 In$_{{\bf 1}-x}$Ga$_{x}$P 梯度合金核无镉量子点的制备及 LED 应用

低毒性磷化铟量子点(indium phosphide quantum dot, InP QD)作为最有可能取代有毒重金属镉基量子点的材料, 已经在下一代商业显示和照明领域中显示出巨大潜力. 然而, 合成具有高荧光量子产率(photoluminescence quantum yield, PL QY)的InP QD 仍然具有挑战性. 因此, 提出了以乙酰丙酮镓作为镓源, 在高温下通过乙酰丙酮基对表面配体的活化作用, 生成具有梯度合金核的 In$_{1-x}$Ga$_{x}$P/ZnSe/ZnS 量子点, 有效解决了原有的 InP 与 ZnSe 之间晶格失配的问题; 同时减少核壳界面缺陷, 使量子点的荧光量子产率高达 82%, 所制备量子点发光二极管(quantum dot light-emitting diode, QLED)的外量子效率(external quantum efficiency, EQE)达到 3.1%. 相比传统的 InP/ZnSe/ZnS 结构量子点, In$_{1-x}$Ga$_{x}$P/ZnSe/ZnS 量子点荧光量子产率提高了 25%, 器件的外量子效率提高了近一倍. 该方案为解决 InP 量子点荧光量子产率低、发光器件性能差等问题提供了新的思路.     

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.     

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     

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

正~~