Polaron And Exciton Effects In Low Dimensional Quantum Wells

Ⅲ-Ⅴ compounds have unique electronic structure and good optical properties and are widely used in various low-dimensional quantum devices as ideal materials for making low-dimensional quantum wells.Transport properties of charge carriers in low-dimensional quantum wells are becoming prominent in the development of condensed matter physics research.Excitons and polarons effects formed by the charge carrier transportation process have always played an important role.As a result,the effective regulation of excitons and polarons is a compelling scientific exploration goal by scholars all the time.Therefore,there are important implications for the development of the semiconductor to investigate exciton and Polaron effects in low-dimensional quantum wells made of Ⅲ-Ⅴ compounds.The polaron effect under the influence of the Rashba effect in group Ⅲ-Ⅴ semiconductor quantum wells is investigated by using Lee-Low-Pines unitary transformation and linear combination operators.The study found that the changes of polaron energy level by the Rashba spin-orbit coupling effect in quantum wells made from Ⅲ-Ⅴ semiconductors were two-fold.On the one hand,the polaron ground state energy and spin splitting energy is affected by Rahsba effect will be split into two branches,and their splitting spacing is positively correlated with the Rahsba spin coupling constant and affected by the nature of the electron-phonon coupling in the material.On the other hand,the ground state energy of the polaron also increases with the increase of the confinement strength.The polaron effect under the influence of the decay magnetic field is investigated by using Lee-Low-Pines unitary transformation and linear combination operators.The study found that the study found that asymmetric gaussian potential is increasing function of itself barrier heigh,is decreasing itself limited range.The magnetic induction intensity of the decay field is positively correlated with the decay magnetic induction intensity,and negatively correlated with the decay frequency and decay time.The ground state energy,the first excited state energy,the excitation energy and the transition frequency of the magnetopolaron is the increasing function of the barrier heigh of the asymmetric Gaussian quantum well and the decay magnetic induction intensity of decay magnetic field,and the decreasing function of the limited range of the asymmetric Gaussian quantum well and the decay frequency and decay time of decay magnetic field.The ground state binding energy of magneopolaron is the decreasing function of the barrier heigh of asymmetric Gaussian quantum well and the decay magnetic induction intensity of the decay magnetic field,the increasing function of the limited range of asymmetric Gaussian quantum well and the decay frequency and decay time of the decay magnetic field.The polaron effect of exciton in Ga_1-xAl_xAs crystals has been investigated using Lee-Low-Pines unitary transformation and linear combination operators.The study found that the Ga_1-xAl_xAs semiconductor bandgap energy changes due to the increase of Al concentration,and transition from direct band gap to indirect band gap after Al>0.45.The ground-state binding energy of the exciton has been increasing with increasing Al concentration and decreasing with increasing confinement strength,regardless.When the Ga_1-xAl_xAs semiconductor is a direct semiconductor,the increase of Al concentration will increase the exciton ground state energy,and when the Ga_1-xAl_xAs semiconductor is an indirect semiconductor,the change of exciton ground state energy becomes significantly slower when the Al concentration increases.