Influences of asymmetric quantum wells on electron-phonon interactions

We calculate the electron capture rates for electrons at the bottom of the first subband above a CdSe quantum well surrounded by ZnSe and ZnS barrier layers. The electron capture mechanism is defined as the transition of an electron at the bottom of the first subband above the quantum well into all possible subbands within the quantum well by the emission of optical phonons, described here by the dielectric continuum model. The asymmetry of the structure influences the shape of the interface modes which must be taken into account together with the confined modes in each material. It is found that the capture rates depend on the width of the quantum well. At regular intervals of well width sharp peaks appear which correspond to electron and phonon resonances. Furthermore the asymmetry of the structure does not allow the capture rates to drop to very small values unlike the symmetric quantum well (e.g. GaN/AlN).