Polaron Effects on Nonlinear Optical Properties of a Hydrogenic Impurity in a CdTe/ZnTe Quantum Dot

Abstract

Hydrogenic donor impurity binding energy is obtained in a ZnxCd1−xTe/ZnTe strained quantum dot taking into account the phonon con nement e ect. The interaction of the electron and the phonon modes are expressed in terms of the Frohlich interaction Hamiltonian. The binding energy is obtained for various Zn composition using the Aldrich Bajaj e ective potential. Calculations have been obtained using the Bessel function as an orthonormal basis for di erent con nement potentials of barrier height considering the internal electric eld induced by the spontaneous and piezoelectric polarizations. Polaron induced linear and third-order nonlinear optical absorption coe cients and the changes of refractive index as a function of incident photon energy are observed. Our results coincide with the recent observations of a hydrogenic impurity binding energy in a CdTe/ZnTe quantum dot solved analytically. It is observed that the potential taking into account the e ects of phonon makes the hydrogenic binding energies larger than the obtained results using a Coulomb potential screened by a static dielectric constant and the optical properties of hydrogenic impurity in a quantum dot are strongly a ected by the con ning potential and the quantum size. It is found that the geometry of the quantum dot, zinc concentration and the e ect of phonon have a great in uence on the absorption coe cient and refractive index changes of the dot. It is also observed that the magnitude of the absorption coe cients enhances with the inclusion of phonon e ect.