Influence of temperature and LO phonon on the effective mass of bipolarons in polar semiconductor quantum dots

Abstract

The temperature and LO phonon effects of the bipolaron in polar semiconductor quantum dots (QDs) are studied by using the Tokuda modified linear-combination operator method and the Lee-Low-Pines variational method. The expressions for the mean number of LO phonons and the effective mass of the bipolaron are derived. Numerical results show that the mean number of LO phonons of the bipolaron decreases with increasing the temperature and the relative distance r between two electrons, but increases with increasing the electron-phonon coupling strength α. The effective mass of the bipolaron M* increases rapidly with increasing the relative distance r between two electrons when r is smaller, and it reaches a maximum at r ≈ 4.05rp, while after that, M* decreases slowly with increasing r. The effective mass of the bipolaron M* decreases with increasing the temperature. The electron-phonon coupling strength markedly influences the changes of mean number of LO phonons and the effective mass M* with the relative distance r and the temperature parameter γ.