Piezoelectric potentials and carrier lifetimes in strain-induced quantum well dots

Abstract

The piezoelectric effect and its influence on the electronic structure of strain-induced quantum dots has been analyzed by elastic continuum and $\mathbf{k}\ensuremath{\cdot}\mathbf{p}$ methods. The piezoelectric effect gives rise to side minima for electrons and holes. These minima are located a few tens of nanometers apart from each other and from the deformation-potential minima. The carriers confined in these minima have radiative lifetimes that are $2\ifmmode\times\else\texttimes\fi{}{10}^{3}$ longer than the lifetime of carriers in the quantum dot ground state. Under quasiequilibrium conditions confinement of a free electron and a hole in the piezominima is energetically \ensuremath{\sim}105 meV more favorable than exciton formation followed by confinement in the deformation potential minima. This suggests that with increasing photoexcitation intensity confinement of electrons and holes in the piezominima will largely cancel the piezoelectric polarization of the structure.