共查询到10条相似文献,搜索用时 308 毫秒
1.
S. Ban X.X. Liang 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(1):153-158
The interface polaron states in a heterojunction are discussed by considering an energy-band bending near the interface and
the influence of an image potential. The ground state energy and the effective mass of a polaron are variationally calculated.
The numerical results for the GaAs/
heterojunction are given. It is shown that even though the influences from bulk longitudinal optical (LO) phonons are more
important for the heterojunctions with lower Al composition, the contributions from two branches of interface optical (IO)
phonons are not negligible. For the heterojunctions with higher Al composition, both the influences from LO phonons and two
branches of IO phonons are important. The band-bending plays an important role for the interface localization of polarons,
but the influence of the image potential is not essential.
Received: 4 November 1997 / Revised and Accepted: 9 March 1998 相似文献
2.
X. P. Bai S. L. Ban 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(1):31-36
A variational method and a memory function approach are
adopted to investigate the electron mobility parallel to the interface for a
model AlxGa1-xAs/GaAs heterojunction and its pressure effect by
considering optical phonon modes (including both of the bulk longitudinal
optical (LO) in the channel side and interface optical (IO) phonons). The
influence of a realistic interface heterojunction potential with a finite
barrier and conduction band bending are taken into account. The properties
of electron mobility versus Al concentration, electronic density and
pressure are given and discussed, respectively. The results show that the
electron mobility increases with Al concentration and electronic density,
whereas decreases with pressure from 0 to 40 kbar obviously. The Al
concentration dependent and the electron density dependent contributions to
the electron mobility from the scattering of IO phonons under pressure
becomes more obvious. The variation of electron mobility with the Al
concentration and electron density are dominated by the properties of IO and
LO phonons, respectively. The effect of IO phonon modes can not be neglected
especially for higher pressure and electronic density. 相似文献
3.
We have study the simultaneous effect of Rashba and Dresselhaus spin–orbit interactions on the polaron properties in wurtzite semiconductor quantum wells. The linear and cubic contributions of the bulk Dresselhaus spin–orbit coupling and the effects of phonon confinement on electron–optical-phonon interaction Hamiltonians are taken into account. We have found analytical solutions for the polaron energies as well as polaron effective mass within the range of validity of perturbation theory. It is shown that the polaron energy and effective mass correction are both significantly enhanced by the spin–orbit coupling. Wave number dependent phonon contribution on the electron energy has minima and varies differently of the spin-up and spin-down states. Polaron self-energy due to interface optical phonon modes has larger values than of the confined optical phonon modes ones. The polaron effective mass exhibits anisotropy and the contribution of the Dresselhaus spin–orbit coupling term on the polaron effective mass is dominated by Rashba one. 相似文献
4.
A variational method is used to study the ground state of a bound polaron in a weakly oblate wurtzite GaN/AlxGa1 − xN ellipsoidal quantum dot. The binding energy of the bound polaron is calculated by taking the electron couples with both branches of LO-like and TO-like phonons due to the anisotropic effect into account. The interaction between impurity and phonons has also been considered to obtain the binding energy of a bound polaron. The results show that the binding energy of bound polaron reaches a peak value as the quantum dot radius increases and then diminishes for the finite potential well. We found that the binding energy of bound polaron is reduced by the phonons effect on the impurity states, the contribution of LO-like phonon to the binding energy is dominant, the anisotropic angle and ellipticity influence on the binding energy are small. 相似文献
5.
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
6.
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
7.
8.
Polaronic effects on the energy levels of a double donor impurity in quantum wells in the presence of a magnetic field 总被引:3,自引:0,他引:3
Zi-xin Liu Zhen-jiang Lai Yong-chang Huang Ya Liu Guo-jun Cheng 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(3):347-350
In the presence of a magnetic field the Hamiltonian of the single or double polaron bound to a helium-type donor impurity
in semiconductor quantum wells (QWs) are given in the case of positively charged donor center and neutral donor center. The
couplings of an electron and the impurity with various phonon modes are considered. The binding energy of the single and double
bound polaron in AlxlGa 1-xlAs/GaAs/AlxrGa 1-xrAs QWs are calculated. The results show that for a thin well the cumulative effects of the electron-phonon coupling and the
impurity-phonon coupling can contribute appreciably to the binding energy in the case of ionized donor. In the case of neutral
donor the contribution of polaronic effects are not very important, however the magnetic field significantly modifies the
binding energy of the double donor. The comparison between the binding energies in the case of the impurity placed at the
quantum well center and at the quantum well edge is also given.
Received 16 February 1999 相似文献
9.
X. L. Yu S. L. Ban 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(4):483-491
The Larsen perturbation method is adopted to study the
influence of magnetic fields on polarons in realistic heterojunctions in a
quasi-two-dimension approximation. The interaction between an electron and
both the bulk longitudinal optical phonons and the two branches of interface
optical phonons is taken into account to show the influence of magnetic
fields at different ranges on the polaron cyclotron mass due to the coupling
of the electron with each branch of phonon modes. The result indicates that
not only do the bulk phonons influence the polaron cyclotron mass, but the
interface phonons do as well. The pressure effect on the cyclotron mass is
also discussed. 相似文献
10.
Zeng-Ru Zhao 《Physica B: Condensed Matter》2009,404(16):2359-2363
The variational method and the effective mass approximation are applied to calculate the binding energies of the hydrogenic impurity states in a cylindrical quantum wire with finite deep potential well. The phonon effects on the impurity states are considered by taking both the couplings of the electron-phonon and the impurity ion-phonon into account. The numerical results for the GaAs cylindrical quantum wire are given and discussed. It is found that the ion-phonon interaction reduces the impurity binding energy and supplies key contribution to the energy shift, but the electron-phonon coupling enhances the binding energy less. Longitudinal optical (LO) phonons play more important role than interface optical (IO) phonons in the impurity potential screening. The polaron effect caused by LO phonons is more important when the wire is thinner, otherwise the LO phonons are dominant for the thicker wires. 相似文献