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1.
A variational scheme of the Pekar type is employed to study the strong-coupling optical polaron on the outer surface of the polar crystal under the influence of a magnetic field. The ground state energy and the effective mass of the polaron are obtained as functions of the magnetic field strength and the electron-surface optical phonon coupling constant. It is shown that the effective mass of the surface polaron appears in nonisotropic nature due to the coupling between the electron and the surface optical phonon. 相似文献
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Hsu-Cheng Hsu 《Solid State Communications》2004,131(6):371-375
The coupling strength of the radiative transition of hexagonal ZnO nanowires to the longitudinal optic (LO) phonon polarization field is deduced from temperature dependent photoluminescence spectra. An excitonic polaron formation is discussed to explain why the interaction of free excitons with LO phonons in ZnO nanowires is much stronger than that of bound excitons with LO phonons. The strong exciton-phonon coupling in ZnO nanowires affects not only the Haung-Ray S factor but also the FXA-1LO phonon energy spacing, which can be explained by the excitonic polaron formation. 相似文献
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Interface polarons in a realistic heterojunction potential 总被引:9,自引:0,他引:9
S.L. Ban J.E. Hasbun 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,8(3):453-461
The ground states of interface polarons in a realistic heterojunction potential are investigated by considering the bulk and
the interface optical phonon influence. A self-consistent heterojunction potential is used and an LLP-like method is adopted
to obtain the polaron effect. The numerical computation has been done for the Zn1-xCdxSe/ZnSe system to obtain the polaron ground state energy, self energy and effective mass parallel to the interface. A simplified
coherent potential approximation is developed to obtain the parameters of the ternary mixed crystal and the energy band offset
of the heterojunction. It is found that at small Cd concentration the bulk longitudinal optical phonons give the main contribution
for lower areal electron densities, whereas the interface phonon contribution is dominant for higher areal electron densities.
The interface polaron effect is weaker than the effect obtained by the three dimensional bulk phonon and by the two dimensional
interface phonon models.
Received 17 September 1998 相似文献
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量子阱中极化子的声子平均数 总被引:8,自引:2,他引:6
采用有效质量近似下的变分法,考虑到电子同时与表面光学声子和体纵光学声子相互作用,研究了无限深量子阱中极化子的表面光学声子平均数,体纵光学声子平均数和光学声子平均数。讨论了电子与体纵光学声子耦合强度α,阱宽L和势垒材料AlxGa1-xAs中Al的含量x对上述光学声子平均数的影响。以GaAs/AlxGa1-xAs量子阱为例进行了数值计算。结果表明:量子阱中表面光学声子平均数随耦合强度α,阱宽L和Al含量x增大而增大。量子阱中体纵光学声子平均数随耦合强度α,阱宽L的增大而增大。光学声子平均数随耦合强度α,阱宽L和Al含量x的增大而增大。 相似文献
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多原子半无限晶体中表面极化子的内部激发态 总被引:1,自引:1,他引:0
研究多原子半无限晶体中电子与表面光学(SO)声子耦合强,而与体纵光学(LO)声子耦合弱的极化子的激发态性质.采用线性组合算符和幺正变换方法导出与SO声子耦合强而与LO声子耦合弱情形下极化子的基态能量、第一内部激发态能量和激发能量.结果表明,多原子半无限晶体中与SO声子耦合强,而与LO声子耦合弱的极化子的基态能量、第一内部激发态能量不仅包含不同支LO声子和不同支SO声子与电子耦合的能量,而且也包含不同支SO声子之间相互作用贡献的附加能量.激发能量与体纵光学声子无关. 相似文献
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赵翠兰 《原子与分子物理学报》2013,30(6)
采用求解能量本征方程、幺正变换及变分相结合的方法,研究声子和温度对球型量子点中极化子性质的影响。数值计算表明,声子效应导致极化子的基态能量低于电子能量,且极化子基态能量随电子—声子耦合强度的增大而降低。数值计算还表明,温度较低时,声子不会被激发,极化子的基态能量不随温度而变;温度较高时,声子会被激发,导致极化子能量随温度升高而增大。 相似文献
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声子和温度对球型量子点中极化子性质的影响 总被引:1,自引:0,他引:1
采用求解能量本征方程、幺正变换及变分相结合的方法,研究声子和温度对球型量子点中极化子性质的影响.数值计算表明,声子效应导致极化子的基态能量低于电子能量,且极化子基态能量随电子-声子耦合强度的增大而降低.数值计算还表明,当温度较低,使得电子热运动能量小于声子能量时,声子不会被激发,极化子的基态能量不随温度的变化而变化;在温度较高,使得电子热运动能量大于声子能量时,电子和晶格热运动加剧,更多的声子被激发.极化子的基态能量随温度的升高而增大. 相似文献
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A variational approach is used to study the ground state of a bound polaron in a spherical quantum dot under an external electric field. The binding energy of the hydrogenic impurity state is calculated by taking the interaction of an electron with both the confined longitudinal optical phonons and the surface optical phonons into account. The interaction between impurity and longitudinal optical phonons has also been considered to obtain the binding energy of a bound polaron. It shows that the polaron effects give significant corrections to the binding energy and its Stark energy shift. The external electric field increases the phonon contributions to the binding energy. 相似文献
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Y. Toda O. Moriwaki M. Nishioka Y. Arakawa 《Physica E: Low-dimensional Systems and Nanostructures》2000,8(4)
We have investigated the carrier relaxation mechanism in InGaAs/GaAs quantum dots by photoluminescence excitation (PLE) spectroscopy. Near-field scanning optical microscope successfully shows that a PLE resonance at a relaxation energy of 36 meV can be seen in all single-dot luminescence spectra, and thus can be attributed to resonant Raman scattering by a GaAs LO phonon to the excitonic ground state. In addition, a number of sharp resonances observed in single-dot PLE spectra can be identified as resonant Raman features due to localized phonons, which are observed in the conventional Raman spectrum. The results reveal the mechanism for the efficient relaxation of carriers observed in self-assembled quantum dots: the carriers can relax within the continuum states, and make transitions to the excitonic ground state by phonon emission. 相似文献
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The energy levels of a polaron in a wurtzite nitride finite parabolic quantum well (PQW)are studied by a modified Lee-Low-Pines variational method. The ground state of the polaron, the transition energy from first exited state to the ground state and the
关键词:
氮化物抛物量子阱
电子-声子相互作用
极化子 相似文献
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E. A. Zibik L. R. Wilson R. P. Green J. -P. R. Wells P. J. Phillips D. A. Carder J. W. Cockburn M. S. Skolnick M. J. Steer H. Y. Liu M. Hopkinson 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):405
Polaron decay in n-type InAs quantum dots has been investigated using energy dependent, mid-infrared pump–probe spectroscopy. By studying samples with differing ground state to first excited state energy separations the relaxation time has been measured between 40 and 60 meV. The low-temperature decay time increases with increasing detuning between the pump energy and the optical phonon energy and is maximum (55 ps) at 56 meV. From the experimentally determined decay times we are able to extract a low-temperature optical phonon lifetime of 13 ps for InAs QDs. We find that the polaron decay time decreases by a factor of 2 at room temperature due to the reduction of the optical phonon lifetime. 相似文献
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考虑电子与体纵光学声子相互作用时,采用LLP变分方法,研究柱形量子线中极化子性质,导出了柱形量子线中极化子光学声子平均数随量子线截面半径和电子-LO声子耦合强度的变化关系.结果表明柱形量子线中极化子的光学声子平均数随量子线截面半径减小而减小,随电子-LO声子耦合强度增强而增加. 相似文献
14.
The effects of the interaction between electron and bulk longitudinal optical (LO) phonon and surface optical (SO) phonon on the impurity binding energy of the ground state in a polar crystal slab within an external electric field are derived by using the method of a variational wavefunction. The binding energy of the bound polaron is obtained as a function of the impurity position, the slab thickness and the electric field strength. It is found that the polaronic correction to the impurity binding energy by the SO phonon may be enhanced and that by the LO phonon may be reduced with increasing electric field strength. And the effect of the electron-phonon interaction is quite important in increasing the values of binding energy. 相似文献
15.
The polaron self-energy and correction to the electron effective mass in a freestanding quantum wire is investigated by the perturbation approach.The polaron effect of the electron-confined longitudinal optical (LO) phonon and surface optical (SO) phonon interactions are separately worked out. Numerical calculation on a GaAs quantum wire shows that the confined LO phonon contribution to the polaron self-energy is relatively small for a narrow wire and gradually approach that of the bulk material when the radius of the wire increases. While the contribution of the SO phonon modes is big for small wire radius and then decreases as the radius increases. 相似文献
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C. Depeursinge 《Solid State Communications》1978,25(7):499-503
New optical spectra near the fundamental edge of GaSe have been measured at low temperatures. The observed fine structure is explained in terms of transitions to excitonic groundstates and excited states, in terms of phonon replica of exciton ground states and in terms of excitons bound to intrinsic point defects. 相似文献
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Taking into account the tetrahedral shape of a quantum-dot quantum well (QDQW) when describing excitonic states, phonon modes, and the exciton-phonon interaction in the structure, we obtain within a nonadiabatic approach a quantitative interpretation of the photoluminescence spectrum of a single CdS/HgS/CdS QDQW. We find that the exciton ground state in a tetrahedral QDQW is bright, in contrast to the dark ground state for a spherical QDQW. The position of the phonon peaks in the photoluminescence spectrum is attributed to interface optical phonons. We also show that the experimental value of the Huang-Rhys parameter can be obtained only within the nonadiabatic theory of phonon-assisted transitions. 相似文献