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M. M. Voronov E. L. Ivchenko A. N. Poddubnyĭ V. V. Chaldyshev 《Physics of the Solid State》2006,48(9):1814-1819
The optical reflectance spectra of resonant Bragg quantum-well structures are studied theoretically. The existence of two special frequencies in the spectra at which the reflectance depends only weakly on the number of quantum wells in the structure is explained analytically. The effect of nonradiative exciton damping on the reflectance spectra in the vicinity of the special frequencies is analyzed. It is shown that the inclusion of the dielectric contrast leads to the appearance of a third special frequency, at which the contributions to the reflectance due to the dielectric contrast and exciton resonance completely cancel each other. 相似文献
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<正>特种电源是为满足科研、工程等领域特殊负载或特殊应用需求设计研发的电源。特种电源技术研究是电源技术研究领域中与应用目标耦合度较高的一个研究方向,由于应用目标的多样性,使得其技术研究工作富有创新活力,也使其对相关学科的新技术较为敏感。上个世纪中叶, 相似文献
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Boron (B)/phosphorus (P)-doped single-wall carbon nanotubes (B-PSWNTs) are studied by using the first-principle method based
on density function theory. Mayer bond order, band structure, electrons density and density of states are calculated. It concludes
that the B-PSWNTs have special band structure, which is quite different from BN nanotubes, and that metallic carbon nanotubes
will be converted to semiconductor due to boron/phosphorus co-doping, which breaks the symmetrical structure. The bonding
forms in B-PSWNTs are investigated in detail. Besides, Mulliken charge population and the quantum conductance are also calculated
to study the quantum transport characteristics of B-PSWNT hetero-junction. It is found that the position of p–n junction in
this hetero-junction will be changed as the applied electric field increase and it performs the characteristics of diode. 相似文献
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W. A. Schlup 《Journal of statistical physics》1975,12(2):131-143
A Fokker-Planck equation can be derived from a transition-type transport equation if the transition rates are nearly local in momentum space compared with the inhomogeneity length of the distribution. It is a second-order differential equation, whose coefficients depend on the band structureE(k), the viscosity tensor (k), and the temperatureT. Classical solutions of the Fokker-Planck equation deal with the parabolic band structure of free Brownian particles in a field of force. Mobility and diffusivity are then independent of the applied field. Here the explicit solution for the stationary state and the time-integrated conditional probability will be given in one dimension. This suffices to determine mobility and diffusivity. Assuming = 1, these quantities become independent of the field and the band structure, if the latter is nonperiodic, though the distribution still depends on it. This property even holds in three dimensions fork-independent viscosity tensors. Field-dependent mobility and diffusivity are obtained for ak-dependent viscosity or = 1 and periodic band structures. The latter is demonstrated for the caseE-cosk, which is also related to the noise problem in Josephson junctions. 相似文献