BOUND POLARON IN A POLAR SEMICONDUCTOR HETEROJUNCTION IN STATIC ELECTRIC FIELD

Abstract

The binding energy of the ground state of a bound polaron near the interface of a polar-polar semiconductor heterojunction is investigated by using the Lee–Low–Pines intermediate coupling method. The influence of a triangular potential approximation of the interface, the electron-phonon and impurity-phonon interactions as well as the half-space bulk longitudinal and interface-optical phonon modes are all taken into account. We have performed numerical calculations on the GaAs / Al x Ga 1-x As (0.2 ≤ x ≤ 0.4) heterojunction system and studied the relations between the ground state binding energy of the polaron and the impurity position, electric field strength and electron area density, respectively. It is found that with the increase in the distance between the impurity and the interface, the binding energy and the contribution of phonons reach the maximum. It is also found that the binding energy of the bound polaron increases slowly with the increase in an electric field while the total polaronic correction decreases the binding energy. When the electron area density is increased, the contribution of the interface-optical (IO) modes is greater than that of the bulk longitudinal optical (LO) mode.