非对称高斯势量子点中LO声子自发辐射率的研究

本文在偶极近似下,基于费米黄金规则,采用LL P-Pekar幺正变换变分法研究了双参 量非对称高斯势量子点(QD)中体纵光学(LO)声子的自发辐射率,并讨论了它的单参量抛 物势近似,数值结果表明:声子自发辐射率w随电声耦合强度α、色散系数η 的增加而减小,随高 斯势阱深V₀的增加而增大;声子自发辐射率w随高斯势阱宽L的变化呈现非对称“高斯分布”并受到电声 耦合强度α、色散系数η和高斯势阱深V₀的显著影响;选用双参量非对称高斯势VG描写QD中电子的受 限效应能够反映声子自发辐射的更多量子化特性,而其单参量抛物势VP近似给出的结果较为简单和粗糙。

LO phonon spontaneous emission rate in an asymmetric Gauss potential quantum d ot

Under the dipole approximation,based on the Fermi Golden Rule,longit udinal optical (LO) phonons spontaneous emission rate in the two-parameter asy m metric Gauss potential quantum dot is investigated by using the Lee-Low-Pine u ni tary transformation and Pekar-type transformation variational method.Numerical results show that the spontaneous emission rate will decreases with increasing t he electron -phonon coupling strength and the dispersion coefficient,and will i ncreases with increasing the well depth of the asymmetric Gauss potential;the s pontaneous emission rate changes with the well width of the asymmetric Gauss pot ential as a asymmetric "Gaussian distribution" and are significantly affected by the electron -phonon coupling strength,the dispersion coefficient and the wel l depth of asymmetric Gauss potential;selecting two-parameter asymmetric Gauss p otential to describe the confinement effects of electrons in quantum dot can ref lect more quantization characteristics of phonon spontaneous emission rate,whil e the single-parameter parabolic potential approximation of the asymmetric Gaus s potential gives simple and rough results.The influence of the dispersion and t he electron -phonon coupling strength of the materials on the LO spontaneous em i ssion rate in the two-level system cannot be ignored.The results of this paper will help reveal the effects of phonon on the optoelectronic and transport prope rties of quantum dot.