共查询到20条相似文献,搜索用时 109 毫秒
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采用Huybrechts线性组合算符和Lee-Low-Pines变换法研究了温度和极化子效应对量子阱中激子与界面光学声子强耦合又与体纵光学声子弱耦合体系基态的影响,推导出激子基态的诱生势和基态能量的移动的表达式. 以AgCl/AgBr量子阱为例进行了数值计算,结果表明,由激子-界面光学声子强耦合所产生的激子基态的诱生势和基态能量的移动随温度的升高而增大,而由激子-体纵光学声子弱耦合所产生的激子基态的诱生势和基态能量的移动随温度的升高而减小. 相似文献
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采用Huybrechts线性组合算符和Lee-Low-Pines变换法研究了温度和极化子效应对量子阱中激子与界面光学声子强耦合又与体纵光学声子弱耦合体系基态的影响,推导出激子基态的诱生势和基态能量的移动的表达式. 以AgCl/AgBr量子阱为例进行了数值计算,结果表明,由激子-界面光学声子强耦合所产生的激子基态的诱生势和基态能量的移动随温度的升高而增大,而由激子-体纵光学声子弱耦合所产生的激子基态的诱生势和基态能量的移动随温度的升高而减小.
关键词:
量子阱
强耦合激子
极化子效应
温度依赖性 相似文献
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建立了圆柱状量子点量子导线复合系统中激子满足的方程,用微扰论求出激子能量.以CdS/HgS/CdS/HgS/CdS圆柱状量子点量子导线复合系统为例,研究了系统中电子的概率分布和系统线度对激子能量的影响.结果表明:系统中电子、空穴以及激子的能量均随量子点高度h0的增大而减小,电子-空穴相互作用对基态激子能量的影响要大于激发态;电子沿径向方向的概率分布呈起伏状,在轴线和表面附近的概率趋于零,而在R/2附近概率最大;在量子点附近电子沿轴向方向的概率分布呈振荡特征
关键词:
量子点
量子导线
激子
能量 相似文献
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利用B-splines特性构建量子点中激子的波函数,计算PbS量子点中激子的基态能量Eg的量子尺寸效应,并将计算结果与实验结果及其他理论计算结果进行比较;利用B-splines技术计算的激子的基态能量在整个区域与实验完全符合,同时计算了有效质量和势垒高度对基态能量Eg的量子尺寸效应的影响. 相似文献
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本文用动量和位置的线性组合作为算符,计算了极性晶体的表面或界面极化子的基态能量,结果表明,线性组合算符对于研究极性晶体的表面或界面极化子的性质也是适用的。
关键词: 相似文献
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本文考虑了电—声子耦合作用,应用么正变换方法计算了GaAs-Ga1-xAlxAs量子阱中的激子束缚能;得到了激子束缚能随阱宽变化的曲线。当考虑激子声子相互作用后,激子相对于电子极化子和空穴极化子的第一子带底的束缚能小于相应的裸激子的束缚能量。 相似文献
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J. Zhu S. L. Ban S. H. Ha 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(2):67
The binding energy of an exciton screened by the electron-hole plasma in a wurtzite
GaN/In
x
Ga1−x
N quantum well (in
the case of 0.1 < x < 1 within which the interface phonon
modes play a dominant role) is calculated including the exciton-phonon interaction by a
variational method combined with a self-consistent procedure. The coupling between the
exciton and various longitudinal-like optical phonon modes is considered to demonstrate
the polaronic effect which strongly depends on the exciton wave function. All of the
built-in electric field, the exciton-phonon interaction and the electron-hole plasma
weaken the Coulomb coupling between an electron and a hole to reduce the binding energy
since the former separates the wave functions of the electron and hole in the
z direction and the later two enlarge the exciton Bohr radius. The
electron-hole plasma not only restrains the built-in electric field, but also reduces the
polaronic effect to the binding energy. 相似文献
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Transient dynamics of a one‐dimensional Holstein polaron under the influence of an external electric field 下载免费PDF全文
Following the Dirac‐Frenkel time‐dependent variational principle, transient dynamics of a one‐dimensional Holstein polaron with diagonal and off‐diagonal exciton‐phonon coupling in an external electric field is studied by employing the multi‐D2 Ansatz, also known as a superposition of the usual Davydov D2 trial states. Resultant polaron dynamics has significantly enhanced accuracy, and is in perfect agreement with that derived from the hierarchy equations of motion method. Starting from an initial broad wave packet, the exciton undergoes typical Bloch oscillations. Adding weak exciton‐phonon coupling leads to a broadened exciton wave packet and a reduced current amplitude. Using a narrow wave packet as the initial state, the bare exciton oscillates in a symmetric breathing mode, but the symmetry is easily broken by weak coupling to phonons, resulting in a non‐zero exciton current. For both scenarios, temporal periodicity is unchanged by exciton‐phonon coupling. In particular, at variance with the case of an infinite linear chain, no steady state is found in a finite‐sized ring within the anti‐adiabatic regime. For strong diagonal coupling, the multi‐ Anstaz is found to be highly accurate, and the phonon confinement gives rise to exciton localization and decay of the Bloch oscillations.
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《Superlattices and Microstructures》2005,37(1):43-53
We study theoretically the interaction between excitons and longitudinal optical (LO) phonons in a cylindrical disk-like semiconductor quantum dot under an applied magnetic field. Due to the intensity of the interaction in the strong coupling regime, a composite quasi-particle called exciton–polaron is formed. We focus on the effect of the disk size and an external magnetic field on the exciton–phonon interaction energy and the exciton–polaron modes. The numerical computation for a CdSe quantum disk have shown that the exciton–phonon interaction energy is very significant and is even dominant when the disk height is small, which leads to a large Rabi splitting between the exciton–polaron modes. We investigate also the effect of the temperature on the integrated photoluminescence (PL) intensity, and show that at relatively high temperature the LO phonons have a noticeable effect on it. This physical parameter also shows a great dependence on quantum disk size and on magnetic field. 相似文献
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Based on the pseudopotential method under the virtual crystal approximation that takes into account the effect of compositional disorder, the electron and heavy-hole effective masses and the dielectric constants in GaxIn1−xAs (0≤x≤1) have been calculated. The results are firstly used in the Wannier equation, which allowed the determination of the exciton reduced mass, binding energy and Bohr radius; then, the polaron properties have been investigated. In this respect, the Fröhlich coupling parameter, Debye temperature and polaron effective mass are calculated and their dependence on the Ga concentration is examined. For InAs and GaAs, our results are generally in reasonable agreement with the known data in the literature, while for compositions x in the range 0-1, our treatment represents the first theoretical predictions. It is found that the exciton and polaron properties for compositions 0<x<1 differ from those of the parent compounds suggesting thus more diverse opportunities to describe most exciton and polaron properties in ternary mixed crystals of interest. 相似文献
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Z. P. Wang X. X. Liang X. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):41-46
Polaron effects on excitons in parabolic quantum wells are
studied theoretically by using a variational approach with the so-called
fractional dimension model. The numerical results for the exciton binding
energies and longitudinal-optical phonon contributions in
GaAs/Al0.3Ga0.7As parabolic quantum well structures are obtained as functions of the well width. It is shown that the exciton binding energies
are obviously reduced by the electron (hole)-phonon interaction and the polaron effects are un-negligible. The results demonstrate
that the fractional-dimension variational theory is effectual in the investigations of excitonic polaron problems in parabolic
quantum wells. 相似文献
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A study has been carried out of the temperature dependences of luminescence spectra on a large number of CdTe/ZnTe structures
differing in average thickness, 〈L
z〉=0.25–4 monolayers (ML), and CdTe layer geometry (continuous, island type). The influence of geometric features in the structure
of ultrathin layers on linewidth, the extent of lateral localization of excitons, their binding energy, and exciton-phonon
coupling is discussed. It is shown that in island structures there is practically no lateral exciton migration. The exciton-phonon
coupling constant in a submonolayer structure has been determined, Γph=53 meV, and it is shown that in structures with larger average thicknesses Γph is considerably smaller. Substantial lateral exciton migration was observed to occur in a quantum well with 〈L
z〉=4 ML, and interaction with acoustic phonons was found to play a noticeable part in transport processes. It has been established
that the depth of the exciton level in a quantum well and structural features of an ultrathin layer significantly affect the
temperature dependences of integrated photoluminescence intensity.
Fiz. Tverd. Tela (St. Petersburg) 41, 717–724 (April 1999) 相似文献
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The theory of exciton polaron in quantum well is developed. The interaction with symmetric interface phonons is shown to contribute significantly to polaron exciton binding energy. As a result, this energy depends both on effective masses of charge particles in the quantum well and on polarization properties of the barriers. The conditions are found for strong exciton–phonon coupling in quantum well. 相似文献