Image Charge and Electric Field Effects on Hydrogen-like Impurity-bound Polaron Energies and Oscillator Strengths in a Quantum Dot

Abstract

By using Landau–Pekar variational method, the ground and the first excited state energies and the transition frequencies between the ground and the first excited states of a hydrogen-like impurity-bound polaron in a spherical quantum dot (QD) have been studied by taking into account the image charge effect (ICE). We employ the dielectric continuum model to describe the phonon confinement effects. The oscillator strengths (OSs) of transitions from the 1s-like state to excited states of 2s, 2px, and 2pz symmetries are calculated as functions of the applied electric field and strength of the confinement potential. We have shown that with and without image charge effect, the increase of the strength of the parabolic confinement potential leads to the increase of the oscillator strengths of 1s − 2px and 1s − 2pz transitions. This indicates that the energy differences between 1s- and 2px- as well as 1s- and 2pz-like states have a dominant role determining the oscillator strength. Although there is almost no difference in the oscillator strengths for transitions 1s − 2px and 1s −2pz when the image charge effect is not taken into account, it becomes significant with the image charge effect.