量子点中弱耦合束缚极化子的内部激发态性质

Properties of Internal Excited State of the Weak-coupling Bound Polaron in a Quantum Dot

采用线性组合算符和幺正变换方法研究库仑束缚势对量子点中弱耦合束缚极化子激发态性质的影响。计算了束缚极化子的振动频率、第一内部激发态能量、激发能量和共振频率随量子点的有效受限长度,电子-声子耦合强度和库仑束缚势的变化关系。结果表明:量子点中弱耦合束缚极化子的振动频率、第一内部激发态能量、激发能量和共振频率随量子点的有效受限长度的减少而迅速增大,随库仑束缚势的增加而增大。

With the quick development of the semiconductor growth technology, people have produced kinds of quantum dots. Due to the novel optoelectronic properties and the transport characteristics of quantum dots, there will be a widely applied prospect for them. In recent years, the physical characteristic of a bound polaron in a quantum dot has been of considerable interest. Many investigators studied the properties of the bound polaron in a quantum dot by means of various theoretical and experimental methods. Recently, the properties of bound polaron in quantum dot were studied by using a linear combination operator method by the present authors. However, the properties of the excited state of the bound polaron in a quantum dot have not been investigated so far. In this paper, the properties of the excited state of the weak-coupling bound polaron in a quantum dot were studied by using a linear combination operator and unitary transformation method. The relations of the vibrational frequency of the weak coupling bound polaron in a quantum dot with the effective confinement length of the quantum dot and the Coulomb bound potential are derived. Relation of the first internal excited state energy, the excitation energy and resonance frequency of the weak-coupling bound polaron in a quantum dot with effective confinement length of quantum dot, the electron-phonon coupling strength and the Coulomb bound potential are calculated. The numerical results show that the vibrational frequency, the first internal excited state energy, the excitation energy and the resonance frequency of the weak-coupling bound polaron in a quantum dot will increase strongly with decreasing the effective confinement length of the quantum dot and increase with increasing the Coulomb bound potential. The first internal excited state energy will increase with decreasing the electron-phonon coupling strength