Influence of polaron effects on the ground state of weak-coupling exciton in semiconductor quantum dots

Abstract

The influence of polaron effects on the effective potential of weak-coupling exciton in semiconductor quantum dots (QDs) is studied based on the Lee-Low-Pines-Huybrechts variational method. The results show that the effective potential of the exciton consists of three parts: coulomb potential, induced potential and confining potential. Numerical calculations for the GaAs quantum dot, as an example, are performed. The result indicates that the effective potential of the exciton increases with the electron-hole distance. It is found that the polaron effects have remarkable influence on the states of the exciton: helpful to the stability of the light-hole exciton, but unfavorable to the stability of the heavy-hole exciton.The exciton effects have significant influence on the physical processes (such as optical absorption, luminescence, lasing, optical non-linear action and so on) in semiconductors and have an important application in the research and development of semiconductor optoelectronic devices. In the quantized low-dimensional electronic structure, especially in the quantum dot (QD) structure under three-dimensional (3D) confinement, it has been found experimentally that the binding energy of the exciton is much larger than that in 3D semiconductor materials, and the exciton effects become more strong and stable under higher temperature or electric field [1][2][3] . To theoretically explain the optical experimental results of the QD, the exciton theory of the QD was developed. Hui [4] studied the effect of dielectric constant on the exciton , s ground-state energy of CdSe quantum dots based on the effective mass approximation model. Zhang et al. [5] solved the ground state of excitons confined in spherical core-shell quantum-dot quantum-well nanoparticles using the stochastic variational method. Dong et al. [6] studied the exciton states in vertically stacked self-assembled quantum disks by the effective mass approximation. Xie [7] discussed an exciton trapped by a Gaussian confining potential QD by means of the method of numerical diagonalization of Hamiltonian in the effective-mass approximation. Dou et al. [8] studied the size dependence of biexciton binding energy in a single QD using an atomic force microscopy and micro-photoluminescence measurements. Furthermore, Liu et al. [9] investigated the influence of spin on the properties of strong coupling magnetopolarons in semiconductor quantum dots. In this paper, the influence of polaron effects on the ground state of weakcoupling exciton in semiconductor QDs is studied based on the Lee-Low-Pines-Huybrechts variational method for the first time. The results indicate that the polaron effects have remarkable influence on the states of the exciton. This work can provide some references to explain the photoelectric properties of QDs. We consider an exciton bound in a parabolic QD within the effective mass approximation, and the Frolich Hamiltonian of the interaction system among electrons, holes and longitudinal optical (LO) phonons can be written as where R a...

Modeling and simulation of InAs/GaAs quantum dot lasers

“…Among various kinds of QD lasers, the InAs/GaAs QD laser lasing at 1.3 m can be widely used in optical communication and its typical properties make it different [4][5][6][7][8][9][10] . The device prototype in this paper based on InAs/GaAs QD laser is fabricated in dots in a well (DWELL) structure.…”