声子之间相互作用对量子点中极化子性质的影响

研究了抛物量子点中弱耦合极化子的性质。采用线性组合算符和微扰法,导出了抛物量子点中极化子的基态能量。当计及电子在反冲效应中发射和吸收不同波矢的声子之间的相互作用时,讨论了对量子点中极化子的基态能量的影响。通过数值计算,结果表明,量子点中极化子基态能量随量子点的有效受限长度的减小而迅速增大,随电子-LO声子的耦合强度的增加而减少。当l₀>1.4时,声子之间的相互作用不能忽略。

Influence of Interaction between Phonons on Properties of Polaron in a Quantum dot

Recently,with the quick development of nanofabrication technology to material,the physical cha-racteristics of low dimensional material have aroused great interest.The electron energy spectrum of such quantum dot is fully quantized.Such systems are of great interest in fundamental studies,as well as in practical application for microelectronic devices.Electron-phonon interaction,which plays an important role in electronic and optical properties of polar crystalline materials in three dimensions,will have pronounced effects in low-dimensional systems as well.The properties of polaron in quantum dot have been studied by many theoretical and experiment methods.Zhu and Gu studied the ground state and self-energy of the weak-coupling polaron in a quantum dot by using the second order Rayleigh-Sch rdinger perturbation theory.Using the Fock approximation of Matz and Burkey,Lepine and Bruneau discussed the effect of an anisotropic confinement on the ground state energy of a polaron in a parabolic quantum dot.Mukhopadhyay and Chatterjee investigated the polaronic corrections to the first excited state energy of an electron in a parabolic quantum dot using a canonical transformation method based on the L.L.P.G formation.Li and Zhu investigated the strong coupling polaron in a parabolic quantum dot by the Landau-Pekar variational treatment.It is shown that both the polaron binding energy and the average number of virtual phonons around the electron decrease with increasing the effective confinement length.The results indicate that the polaronic effects are more pronounced in quantum dots than those in two-dimensional and three-dimensional cases.With the use of variational approach,the effects of the bulk-LO phonon on the impurity binding energy in a GaAs quantum dot are studied by Es-sbai et al.Upon using a curvilinear coordinates system,Cantele et al.calculated the effective mass for a particle confined in an ellipsoidal quantum dot.Xie proposed a procedure to calculate the polaron effect of D^- centers in quantum dots with a parabolic laternal confining potential by using the method of few-body physics.The properties of the polaron in a parabolic quantum dot are investigated by using a linear combination operator method by the present author and co-workers.However,so far research of the polaron in a quantum dot only was restricted to the approximation and calculation where the interaction between phonons of different wave vectors in the recoil process is neglected.The ground state energy of the polaron in parabolic quantum dot is derived by using a linear combination operator and perturbation methods.Considering interaction between phonons of different wave vectors in the recoil process,the influence on the ground state energy of polaron in quantum dot is discussed.Numerical calculations shown that the ground state energy of polaron in quantum dot will increase strongly with decreasing the effective confinement length and ground state energy will decrease with increasing the electron-LO phonon coupling strength.When l₀＜1.4,the interaction between phonons can not be ignored in a parabolic quantum dot.