Polarizabilities of shallow donors in spherical quantum dots with parabolic confinement

Abstract

The binding energy and impurity polarizability of hydrogenic donors in a spherical quantum dot of Cd 1 − x in Mn x in Te / Cd 1 − x out Mn x out Te structure are presented assuming parabolic confinement. Within the effective mass approximation, the effects of electric field, as a function of dot size, are discussed on the results obtained using a variational method. The results show that the impurity binding energy (i) increases with the reduction in dot sizes, (ii) decreases in an electric field—this decrease is more prominent for wider dots whereas for narrow dots the electric field seems to be unimportant, (iii) increases to a maximum value around the effective Bohr radius, i.e., 60 Å, and then decreases as the size of the dot increases, and (iv) the polaronic effects are suppressed when an electric field is coupled. Spin polaronic shifts are estimated using a mean field theory. The results show that the spin polaronic shift decreases as the electric field and dot radius increase. These results are compared with the existing literatures.