Influences of asymmetric quantum wells on electron-phononinteractions

Abstract

We calculate the electron capture rates for electrons at the bottom of thefirst subband above a CdSe quantum well surrounded by ZnSe and ZnS barrierlayers. The electron capture mechanism is defined as the transition of anelectron at the bottom of the first subband above the quantum well into allpossible subbands within the quantum well by the emission of optical phonons,described here by the dielectric continuum model. The asymmetry of thestructure influences the shape of the interface modes which must be takeninto account together with the confined modes in each material. It is foundthat the capture rates depend on the width of the quantum well. At regularintervals of well width sharp peaks appear which correspond to electron andphonon resonances. Furthermore the asymmetry of the structure does not allowthe capture rates to drop to very small values unlike the symmetricquantum well (e.g. GaN/AlN).