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基于密度泛函理论框架的第一性原理平面波赝势方法对双轴应变Si/(111) Si1-xGex(x=0.1—0.4)的能带结构进行了研究,结果表明:导带带边六度简并没有消除;应变部分消除了价带带边的简并度;导带带边能量极值k矢位置和极值附近可由电子有效质量描述的能带形状在应变条件下几乎不变;价带极大值附近可由空穴有效质量描述的能带形状随着x有规律地变化. 此外,给出的禁带宽度与x的拟
关键词:
应变硅
能带结构
第一性原理 相似文献
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首先计算了(001)晶面单轴应变张量,在此基础上采用结合形变势理论的K ·P微扰法建立了在(001)晶面内受任意方向的单轴压/张应力作用时,应变硅材料的能带结构与应力(类型、大小)及晶向的关系模型,进而分析了不同单轴应力(类型、大小)及晶向对应变硅材料导带带边、价带带边、导带分裂能、价带分裂能、禁带宽度的影响.研究结果可为单轴应变硅器件应力及晶向的选择设计提供理论依据.
关键词:
单轴应变硅
K ·P法
能带结构 相似文献
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采用密度泛函理论广义梯度近似第一性原理计算的方法研究了n型Ga掺杂的纤锌矿结构氧化物ZnO的晶格结构、能带结构和态密度,在此基础上分析了其电性能.计算结果表明,掺杂ZnO氧化物晶格a,b轴增大,c轴略有减小;Ga掺杂ZnO氧化物两能带之间具有0.6eV的直接带隙,需要载流子(电子)跃迁的能隙宽度较未掺杂的ZnO氧化物减小;掺杂体系费米能级附近的态密度大大提高,其能带主要由Gas态、Zns态和Os态电子构成,且他们之间存在着强相互作用,其中Gas态电子对导带贡献最大.电输运性能分析结果表明,Ga掺杂ZnO氧化物导电机构由Znp-Op电子在价带与导带的跃迁转变为Gas-Znd-Os电子在价带与导带的跃迁,这也表明Gas态电子在导电过程中的重要作用;掺杂体系费米能级附近的载流子有效质量较未掺杂体系增大,且价带中的载流子有效质量较大,导带中的载流子有效质量较小. 相似文献
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按照Peressi等的第一性原理赝势计算得到的原子几何构形及能带边不连续值,采用紧束缚方法计算了生长在Si(001)衬底上的超晶格(Si_2)_4/(GaAs)_4的电子能带结构及光跃迁振子强度.相应于两种不同的原子几何构形:X端界面及Y端界面情况,超晶格具有不同的基本带隙.但是不管哪种情况,它们都存在能量近乎简并的两类导带底能谷——Γ能谷及△能谷,它们的价带顶都处在Γ点.X端界面超晶格的价带顶附近的状态主要由GaAs层的价态波函数组成.对于Y端界面超晶格的价带顶附近的状态,Si层和GaAs层的价态波函数 相似文献
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通过合金化改性技术,Ge可由间接带隙半导体转变为直接带隙半导体.改性后的Ge半导体可同时应用于光子器件和电子器件,极具发展潜力.基于直接带隙Ge1-x Sn x半导体合金8带Kronig-Penny模型,重点研究了其导带有效状态密度、价带有效状态密度及本征载流子浓度,旨在为直接带隙改性Ge半导体物理的理解及相关器件的研究设计提供有价值的参考.研究结果表明:直接带隙Ge1-x Sn x合金导带有效状态密度随着Sn组分x的增加而明显减小,价带有效状态密度几乎不随Sn组分变化.与体Ge半导体相比,直接带隙Ge1-x Sn x合金导带有效状态密度、价带有效状态密度分别低两个和一个数量级;直接带隙Ge1-x Sn x合金本征载流子浓度随着Sn组分的增加而增加,比体Ge半导体高一个数量级以上. 相似文献
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J. Purić S. Djeniže J. Labat Lj. Ćirković 《Zeitschrift für Physik A Hadrons and Nuclei》1974,267(1):71-75
Spectral lines emited by first three ionisation species of silicon were studyed in a wide range of plasma parameters. The silicon was present as an impurity in the argon plasma created in an electromagneticT tube. Four various condenser bank energies give the plasma in a range of temperatures 8700 to 16400°K and electron concentrations 2.95·1017 cm?3to 5.6·1017 cm?3. Measured line widths and shifts were compared with theories of Griem [1, 2] and Sahal Brechet [3, 10]. The agreement is reasonably good, the measured values are in general smaller than calculated ones. 相似文献
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《Journal of Physics and Chemistry of Solids》2014,75(4):518-522
In this study, we prepared Si clathrate films (Na8Si46 and NaxSi136) using a single-crystalline Si substrate. Highly oriented film growth of Zintl-phase sodium silicide, which is a precursor of Si clathrate, was achieved by exposing Na vapour to Si substrates under an Ar atmosphere. Subsequent heat treatment of the NaSi film at 400 °C (3 h) under vacuum (<10−2 Pa) resulted in a film of Si clathrates having a thickness of several micrometres. Furthermore, this technique enabled the selective growth of Na8Si46 and NaxSi136 using the appropriate crystalline orientation of Si substrates. 相似文献
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Yong RenYong-Bin Chen Miao ZhangJiang Zhu Xing-Wang ZhangYou-Yuan Zhao Ming Lu 《Applied Surface Science》2011,257(22):9578-9582
A multilayered Si nanocrystal-doped SiO2/Si (or Si-nc:SiO2/Si) sample structure is studied to acquire strong photoluminescence (PL) emission of Si via modulating excess Si concentration. The Si-nc:SiO2 results from SiO thin film after thermal annealing. The total thickness of SiO layer remains 150 nm, and is partitioned equally into a number of sublayers (N = 3, 5, 10, or 30) by Si interlayers. For each N-layered sample, a maximal PL intensity of Si can be obtained via optimizing the thickness of Si interlayer (or dSi). This maximal PL intensity varies with N, but the ratio of Si to O is nearly a constant. The brightest sample is found to be that of N = 10 and dSi = 1 nm, whose PL intensity is ∼5 times that of N = 1 without additional Si doping, and ∼2.5 times that of Si-nc:SiO2 prepared by co-evaporating of SiO and Si at the same optimized ratio of Si to O. Discussions are made based on PL, TEM, EDX and reflectance measurements. 相似文献
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Recent particle—particle—γ coincident measurements on a 28Si+28Si resonance have suggested “vanishing spin alignments”. New analyses of the spin alignments with a molecular model are presented. It is clarified that due to a triaxial deformation of the total system a wobbling mode (K-mixing) appears to give rise to spin disalignment. 相似文献
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报道了在硅纳米结构中417nm和436nm双峰结构的蓝光发射的实验和理论研究结果.制备了四种包含和没有包含β-SiC纳米晶粒的硅纳米结构,观察到了417nm和436nm的双峰蓝光发射.光致发光谱的分析和微结构的观察揭示了蓝光发射与硅纳米结构中过剩硅缺陷中心的存在有关.计算了由过剩硅原子形成的含有硅空位缺陷的纳米晶粒的电子能级,发现计算所得的态密度的特征与观察到的双峰发射吻合.这项工作提出了在许多硅纳米结构中存在417nm和436nm蓝光发射的一种可能的机制. 相似文献
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Bedrossian PJ 《Physical review letters》1995,74(18):3648-3651
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C Bhattacharya M Rousseau C Beck V Rauch R M Freeman R Nouicer F Haas O Dorvaux K Eddahbi P Papka O Stezowski S Szilner D Mahboub A Szanto de Toledo A Hachem E Martin S J Sanders 《Pramana》2001,57(1):203-207
The possible occurrence of highly deformed configurations is investigated in the 40Ca and 56Ni di-nuclear systems as formed in the 28Si + 12C, 28Si reactions by using the properties of emitted light charged particles. Inclusive as well as exclusive data of the heavy
fragments and their associated light charged particles have been collected by using the ICARE charged particle multidetector
array. The data are analysed by Monte Carlo CASCADE statistical-model calculations using a consistent set of parameters with
spin-dependent level densities. Significant deformation effects at high spin are observed as well as an unexpected large 8Be cluster emission of a binary nature. 相似文献
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The Auger-recombination coefficient is determined to be Cn = 1,7·10?31 cm6 sec?1 and Cp = 1,2·10?31 cm6 sec?1 in Si. The Auger-recombination is not momentum conserving. 相似文献