Electron–acoustic-phonon interaction in core/shell nanocrystals and in quantum-dot quantum wells

Abstract

The vibrational modes of acoustic phonons and the corresponding eigenfrequencies in $\mathrm{Cd}\mathrm{Se}∕\mathrm{Cd}\mathrm{S}$ core/shell nanocrystals and $\mathrm{Cd}\mathrm{S}∕\mathrm{Cd}\mathrm{Se}∕\mathrm{Cd}\mathrm{S}$ quantum-dot quantum wells (QDQWs) are obtained by adopting their corresponding continuum models. In addition to the analytic results of the vibrational modes in the nanocrystals, the numerical solutions of the energy spectra of the phonons are obtained by using the finite-element method. According to the analytic solutions of electrons or holes obtained by the single-band effective-mass approximation and eigenmodes of phonons, we have calculated the energy shifts from the electron(hole)\char21{}acoustic-phonon interaction by the perturbation theory. The dependence of the ground state and the first excited state energy shifts of carriers in the core/shell nanocrystal and QDQW on the nanostructure is also investigated. We found that the parameter, absolute volume deformation potential, and the localization of carriers are two decisive factors in calculating the values of energy shifts.