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51.
运用密度泛函理论体系下的平面波赝势(PWP)和广义梯度近似(GGA)方法,计算研究了闪锌矿结构的ZnS晶体在不同的外界压强下的电子结构. 通过分析发现,随着外界压强的增大,晶格常数和键长在不断缩小,从S原子向Zn原子转移的电荷越来越少,Zn—S键的共价性逐渐增强,Zn原子和S原子的态密度都有不同程度的变化,而且还有向低能量移动的趋势. 当外界压强达到24GPA时,ZnS从直接带隙半导体变成间接带隙半导体,而且随着压强的增大,间接带隙逐渐变小,直接带隙逐渐增大.
关键词:
闪锌矿结构
态密度
能带结构
密度泛函理论 相似文献
52.
53.
一种用于电子纸的电泳液的显示性能研究 总被引:1,自引:0,他引:1
用有机颜料汉沙黄(P.Y.3)、苏丹黑和合适的稳定剂为原料配制了一种性能稳定的电泳显示液.分析了此电泳显示液中颜料微粒的带电机理及其影响因素,研究了在改变电压方向时反射光谱与吸收光谱的变化及其原因,光谱分析结果表明体系中存在的各种吸附使显示效果受到局限,反射谱与吸收谱的变化在表征器件的显示特性时呈现出一致性,器件的反射光强和反射率在不同波长上有区域选择性,同时对比度也有区域选择性,这决定了在监测器件的响应时应选择的波长范围以及可利用的光源.兼顾灵敏性和测试信号强度的需求,选用峰值波长为470 nm的蓝光二极管为光源,电泳槽的厚度为0.2 mm,用荧光光谱仪监测相同周期不同幅值脉冲电压作用下颜料微粒在493 nm波长处的反射光强的变化,并由示波器记录并输出反射光强随驱动电压的变化,还结合相关理论讨论了驱动电压对器件的反射光强和对比度的影响. 相似文献
54.
C.Y. Liu S.F. Yoon J.H. Teng J.R. Dong S.J. Chua 《Applied Physics A: Materials Science & Processing》2008,91(3):435-439
GaInP/AlGaInP triple quantum well (TQW) lasers, grown by metalorganic chemical vapor deposition (MOCVD) using tertiarybutylarsine
(TBAs) and tertiarybutylphosphine (TBP), were fabricated with a pulsed anodic oxidation (PAO) process. The devices worked
at room temperature (RT) with the lowest threshold current density (Jth) of 1.5 kA/cm2 ever reported for GaInP/AlGaInP lasers grown using TBAs and TBP. Temperature dependent (35–250 K) electroluminescence (EL)
study of the GaInP/AlGaInP laser diode showed almost the same luminescence quenching behavior at a high temperature region
(120–250 K), independent of the injection current (100–150 mA). A model involving a nonradiative recombination mechanism was
presented to interpret the EL quenching behavior over the experimental temperature range. The nonradiative recombination centers
in the Al-containing barrier or cladding layer are believed to contribute to the loss of carriers via nonradiative recombination.
PACS 78.60.Fi; 71.20.Nr; 78.67.De; 81.15.Gh; 42.55.Px 相似文献
55.
CHENG Chuanfu SONG Hongsheng LIU Chunxiang REN Xiaorong ZHANG Ningyu TENG Shuyun & XU Zhizhan . Shanghai Institute of Optics Fine Mechanics Chinese Academy of Sciences P. O. Box - Shanghai China . Department of Physics Shandong Normal University Jinan China . Shandong Institute of Architecture Engineering Jinan China 《中国科学G辑(英文版)》2004,47(3):365-380
Speckle fields are the random light wave distributions produced when the light fields are scattered from random surfaces or a random medium. They appear in many optical phenomena that are related to light propagations[1,2] and have found wide appli-cations in a variety of scientific and technical fields. The examples of the recent impor-tant applications of speckles include the analysis of the movement of the granules[3], the three-dimensional imaging for the microstructures of metal nanocryst… 相似文献
56.
Path length difference is the key parameter in two-beam interferometer, especially in low coherence interferometer. It determines the visibility of the interference fringes. In this study, we present a method to determine the path length difference between two arms of a fiber optic Mach–Zehnder interferometer by evaluating the peaks of power distribution of the interference spectrum with a wide band light source. The experimental results are in close agreement with the theoretical calculations. 相似文献
57.
The possible defect models of Y^3+:PbWO4 crystals are discussed by defect chemistry and the most possible substituting positions of the impurity Y^3+ ions are studied by using the general utility lattice program (GULP). The calculated results indicate that in the lightly doped Y^3+ :PWO crystal, the main compensating mechanism is [2Ypb^+ + VPb^2-], and in the heavily doped Y^3+ :PWO crystal, it will bring interstitial oxygen ions to compensate the positive electricity caused by YPb^+, forming defect clusters of [2Ypb^+ +Oi^2-] in the crystal. The electronic structures of Y3+ :PWO with different defect models are calculated using the DV-Xα method. It can be concluded from the electronic structures that, for lightly doped cases, the energy gap of the crystal would be broadened and the 420nm absorption band will be restricted; for heavily doped cases, because of the existence of interstitial oxygen ions, it can bring a new absorption band and reduce the radiation hardness of the crystal. 相似文献
58.
25 fs pulses with energy up to 0.8 mJ from a multi-pass amplifier system have been spectrally broadened from 460 nm to 950
nm due to strong self-phase modulation (SPM) effect in a gas filled hollow fiber. Using a set of chirped mirrors, the ultra-broadband
dispersion compensation was achieved, and the compressed pulses reached their transform limit. Under optimized conditions
we achieved pulses with duration of 5.1 fs and with energy of 400 μJ, corresponding to the peak power up to 80 GW.
Supported by the National Natural Science Foundation of China (Grant Nos. 60608003, 60490280, 60225005 and 60621063) 相似文献
59.
Zhu Qunyan Teng Fei Wang Zhongshun Wang Yalei Lu Nan 《Analytical and bioanalytical chemistry》2019,411(6):1135-1142
Analytical and Bioanalytical Chemistry - We present a universal method to efficiently improve reproducibility and sensitivity of surface-assisted laser desorption/ionization time of flight mass... 相似文献
60.
Zhiwei Cui Jun Zhou Teng Liu Yicong Wang Yue Hu Ying Wang Zhigang Zou 《化学:亚洲杂志》2019,14(12):2138-2148
A series of porphyrin‐containing polyimide (PI) photocatalysts were synthesized by a one‐step solvothermal method. Characterization results revealed that porphyrin was uniformly coupled into the PI framework through covalent bonding and the visible‐light absorption was greatly improved. The photodegradation activity of porphyrin‐containing PIs for methyl orange (MO) under visible light was enhanced significantly, with the highest pseudo‐first‐order rate constant 35 times higher than that of neat porphyrin and 10 times higher than that of porphyrin‐free PI. The enhancement is mainly attributed to an increased light harvesting accompanied by a varied HOMO level, which was clarified by control experiments, characterizations and theoretical calculations. This work provides an insight into multiple effects of dye molecules in dye‐containing heterogeneous photocatalysts. 相似文献