The Stark Effect Of A Polaron In A Quantum Dot Quantum Well Structure

Within the framework of dielectric continuum approximation and the effective mass approximation, the electron-phonon effects on Stark shifts of polarons in quantum dot quantum well structures are studied theoretically by considering the influence of infinite barriers.Firstly, the ground-state energy and Stark shifts of the free polarons are studied theoretically by using a variational approach. The interactions of an electron with both the longitudinal optical phonons and the surface optical phonons are taken into account. The numerical results for a CdS/HgS quantum dot quantum well structure show that the ground-state energy of the polaron increases monotonously with increasing core radius, but decreases with increasing the electric field intensity. The self-trapping energy of the polaron increases when the electric field intensity and core radius increase, respectively. The size of quantum dot quantum well structure gives a significant influence to Stark shifts of the polaron. Then, the binding energy and Stark shifts of the bound polarons are studied theoretically by using a variational approach. The binding energy of the hydrogenic impurity state is calculated by taking the interaction of an electron with both the longitudinal optical phonons and the surface optical phonons into account. The interaction between impurity and longitudinal optical phonons has also been considered to obtain the binding energy of bound polarons. The numerical results for a CdS/HgS quantum dot quantum well structure show that the Stark shift become obvious with increasing the core radius when the outer radius of spherical shell fixed and the electron-phonon effects give significant corrections to the binding energy.