【摘要】 采用Pekar类型的变分方法研究了抛物量子点中强耦合束缚磁极化子的基态和激发态的性质。计算了束缚磁极化子的基态和激发态的能量、光学声子平均数以及束缚磁极化子的共振频率。讨论了这些量对回旋频率和有效束缚强度以及库仑束缚势的依赖关系。数值计算结果表明:量子点中强耦合束缚磁极化子的基态能量和共振频率以及光学声子平均数均随量子点的有效束缚强度的增加而减小,基态能量随库仑束缚势的增加而减小,随回旋频率的增加而增大。更多还原

【Abstract】 With the development of several experimental techniques,for instance, metalorganic chemical vapour deposition, molecular beam epitaxy and electron beam lithography combined with reverse mesa etching, there has been of considerable interest in understanding of hydrogenic-impurity states in low-dimensional semiconductor heterostructures such as quantum wells, quantum wires and quantum dots. In recent years, there has been great interest in investigating quantum dots both theoretically and experimentally. Due to the small structures of QD’s, some physical properties such as optical and electron transport characteristic are quite different from those of the bulk materials. The study of the impurity states in these low dimensional strictures is an important aspect to which many theoretical and experimental works based. Recent investigations in the reduced dimensionality show that the impurity binding energy will be enhanced with the deduction of the dimensionality. In recent years, the problem of a bound magnetopolaron in a quantum dot has been extensively studied. Au-Yeung et al. studied the combined effects of a parabolic potential and a Coulomb impurity on the cyclotron resonance of a three-dimensional bound magnetopolaron by using Larsen’s perturbation method. Chen et al. investigated thickness effecting on energy levels of impurity-bound magnetopolaron in a parabolic quantum dot by the second-order perturbation theory. Khamkhami et al. studied properties of the magneto-bound polaron in CdSe spherical quantum dots in the framework of the effective mass approximation using the strong coupling method (Landau-Pekar approach). Charrour et al. presented a systematic study of the ground state binding energy of a hydrogenic impurity in cylindrical quantum dot subjected to an external strong magnetic field and performed calculations within the effective-mass approximation using the variational procedure and considering an infinite confining potential on all surfaces of the system. Nguyen et al. analyzed magnetic field effects of parabolic confining potentials on the binding energy of hydrogen impurities in quantum dots using a very simple trial function with only one variational parameter. Chen et al. derived ground state properties of the bound magnetopolaron using the linear combination operator and unitary transformation method. One of this paper’s authors by using the linear combination operator and unitary transformation methods achieved the vibration frequency and the average number of phonons of the strong-coupling bound magnetopolaron in a parabolic quantum dot. By using the variational method of Pekar type, we have studied both the ground state and the excited state of strong coupling bound magnetopolaron in parabolic quantum dot. The results show that,with the increasing the effective confinement strength,the ground state energy,the average number of virtual phonons around the electron and the resonance frequency of bound magnetopolaron in parabolic quantum dots are decreased. The ground state energy of bound magnetopolaron in parabolic quantum dots increases with increasing the cyclotron frequency of the quantum dots and decrease with increasing the coulomb potential.更多还原