Bound polaron states in GaAs/Ga_(1-x)Al_xAs cylindrical quantum dot under hydrostatic pressure effect

摘要

A theoretical study of the effect of hydrostatic pressure on the binding energy of shallow hydrogenic impurity in a cylindrical quantum dot (QD) using a variational approach within the effective mass approximation is performed. The hydrostatic stress was applied along the QP growth axis. The interactions between the charge carriers (electron and ion) and different phonon modes; confined longitudinal optical (LO) phonon modes, and top-surface (TSO) and side-surface (SSO) phonon modes are incorporated in our calculation. We focus on the effects of the QP sizes, the impurity position, the hydrostatic pressure, and the polaronic correction. Our numerical findings for GaAs/Ga_(1-x)Al_xAs QD have shown that the binding energy of the shallow donor impurity with and without total phonon influence decays as the impurity moves away from the center to the edge of the QD. The contribution of LO phonon decreases while that of the SO phonon increases as the impurity shifts away from the QD center. However, the quantity of SO phonon correction to the binding energy is quite small and has a relatively unimportant role when we consider the binding energy of an impurity placed in the cylinder center. Furthermore, both the binding energy and its polaronic corrections due to the LO phonon and the SO phonon modes increase linearly with increasing stress and present a qualitative agreement with those obtained in literature.