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91.
In this paper, by the transparent-component-decimation (TCD) method we obtain three kinds of new basic- components (BCs) through simplifying and decomposing the BCs of three-component Thue-Morse (3CTM) sequence. Based on these new BCs we propose a type of basic-structural-units (BSUs) and investigate the optical transmission of the one-dimensional (1D) superlattices composed of these BSUs. It is found that if the substrates of the 1D BSU superlattices are certain, the optical transmission at the central wavelength (CW) will be determined completely by the number and the type of BSUs and has nothing to do with the marshalling sequence. In particular, if the substrates are identical, the numbers of different types of BSUs are all the same and the middle two elements of BSUs constitute a cycle, then no matter whether the system is periodic, or quasiperiodic, or aperiodic, or unordered, or even random, it will be transparent at the CW. The conclusion is confirmed by the numerical results. Similar to the even layers of neighbourhood identical elements in TCD method, such a kind of optical BSU subsystem can also be decimated from the chain in the process of transmission investigation. There would be a potential application in the designing of some interesting optical devices. 相似文献
92.
Summary Thek-conserving selection rule in the electron-hole recombination is investigated by intensity-dependent photoluminescence measurements
inn-type modulation-doped Ga
x
In1−x
As−Al
y
In1−y
As single quantum wells intentionally doped with Be acceptors in the well centre. Thek-non-conserving recombination process involves electrons with momentum up to the Fermi edge and holes localized on the Be
acceptors. The transition from a one-component electron plasma to a two-component electron-hole plasma is studied by comparing
the experimental results with theoretical line shape models. The density-dependent band gap renormalization is determined
for the one-component and the two-component electron-hole plasma. The obtained results are found to agree well with recent
theoretical calculations. 相似文献
93.
S. Pokrant K.B. Whaley 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(2):255-267
We utilize a tight-binding model to study the effects of surface structure on electronic properties of CdSe clusters. The
model takes into account experimental information about structure and shape of the nanocrystals, as well as the nature and
distribution of capping ligands. The effects of both organic capping ligands and inorganic capping shells on the densities
of states (DOS) and on the single-particle absorption spectra of the clusters are calculated for various cluster shapes and
sizes, and are compared to results for clusters with truncated surfaces. For organic capping ligands, the effect of ligand
hybridization is investigated and a simple model of surface reconstruction is developed. Both ligand hybridization and surface
reconstruction are seen to have a major influence on the band edge electronic and optical properties. Inorganic capping shells
give rise to differential localization of valence and conduction band edge states, with the hole primarily confined to the
core region and the electron more evenly distributed over both core and shell.
Received 21 September 1998 / Received in final form: 15 December 1998 相似文献
94.
95.
Summary We show how to compute the optical functions (reflection and transmission) of a semiconductor thin slab, in the vicinity of
nearly degenerate exciton states. Additional boundary conditions are not required in the coherentwave-function approach and
multiple-polariton effects are included since Maxwell equations are satisfied. When the slab thickness is comparable to the
exciton Bohr radius, centre of mass quantization results. When the slab thickness is smaller than the Bohr radius, we obtain,
quantum well polaritons. Numerical examples appropriate to GaAs are given. 相似文献
96.
97.
98.
利用Krönig-Penney 模型和形变势理论,从理论上探讨了纤锌矿型AlN/InN和AlN/GaN超晶格系统的能带结构及不同应变模式对能带结构的影响,计算得到了能带结构随各亚层参量变化的一般性规律、超晶格的能量色散关系、应变造成的影响以及不同亚层厚度的系统禁带宽度和导带第一子禁带宽度.研究发现,通过改变亚层厚度可以从不同形式设计能带结构,应变会改变系统禁带宽度,使带阶和子能带明显窄化,价带结构趋于复杂甚至生成准能带结构.与实验结果对比后发现,该模型适于模拟窄势阱结构超晶格,而对于宽势阱则必须
关键词:
AlN/InN和AlN/GaN超晶格
Krönig-Penney模型
应变
子能带 相似文献
99.
100.
M. Salvato F. Bobba G. Calabrese C. Cirillo A. M. Cucolo A. De Santis A. Vecchione C. Attanasio 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(1):79-85
Resistivity vs. temperature measurements on
La0.7Ca0.3MnO3/YBa2Cu3O7-δ
/La0.7Ca0.3MnO3 (LCMO/YBCO/LCMO) trilayers with different
YBCO thickness, were performed in external magnetic field H up to 8 T. By
evaluating the activation energy U from the slope of the resistivity
Arrhenius plot, a strong depression of U has been observed when decreasing
the YBCO layer thickness and the absolute U values appear to be reduced with
respect to the values reported in literature in the case of YBCO thin films
and YBCO/insulating multilayers. Moreover, a logarithmic U vs. H dependence is
shown both in the case of thick and thin YBCO layers indicating the
formation of a two dimensional vortex lattice. The experimental data are
discussed considering the strong influence of the ferromagnetic LCMO on the
superconducting YBCO properties which reduces the effective YBCO thickness
more than predicted by the conventional theories. 相似文献