抛物形量子点中弱耦合极化子的性质

Property of Weak-coupling Polaron in a Parabolic Quantum Dot

采用线性组合算符和幺正变换方法研究了抛物形量子点中弱耦合极化子的基态能量和束缚能。计算结果表明,基态能量和束缚能随有效束缚强度增加而减小。随着有效束缚强度逐渐加大,最后逐渐趋于体结构极化子的基态能量。当有效束缚强度给定,基态能随电子 体纵光学声子耦合强度增加而减小。由于有效束缚强度与量子点受限强度平方根成反比,所以量子点受限越强,基态能和束缚能越大,电子 体纵光学声子耦合强度的变化对量子点的影响越小。当量子点受限变弱时,电子 体纵光学声子耦合强度变化对量子点的影响变大。所以在量子点弱受限区域,极化子对量子点的影响不容忽略。

In recent years, the rapid advances of nanofabrication technology have made it possible to work with quasi-zero-dimensional quantum dot in laboratories. 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 applications for microelectronic devices. There exist numerous works that have demonstrated the significant influence of electron-phonon interactions on the electronic, optical, and transport properties of microstructures such as quantum wells, quantum wires, and quantum dots. Other people studied the effects of electron-phonon on the quantum dots by the second-order Rayleigh-Schrodinger perturbation theory or the Landau-Pekar variational treatment. In this paper, we investigate weak-coupling polaron's properties in a parabolic quantum dot by the linear combination operator in the first time. It is shown that the ground state energy and binding energy decrease with increasing the effective confined length of the quantum dot. The result presents the polaron ground state energy of parabolic quantum dot is as a function of the effective confinement length. They show the variation of the electron-phonon coupling strength has very small effect on the polaron binding energy of parabolic quantum dot in the profoundly weak effective confinement length field. But, the variation of electron-phonon coupling strength has obvious effect in the strong effective confinement length field. They will turn to bulk structure crystal when the effective confinement length intend to infinite. Also, indicate the polaron binding energy of parabolic quantum dot is as a function of effective confinement length. It is evident that the variation of the electron-phonon coupling constant has no effect on the polaron binding energy of parabolic quantum dot. In one word, the confine of parabolic quantum dot strengthens the ground state energy.