Effects of strain on the band alignment and the optical gain of a CdTe/ZnTe quantum dot

The band lineups at the strained layer interfaces, in Zn_xCd_1-xTe/ZnTe quantum dot nanostructure for various Zn alloy content, are computed using model solid theory with an example of CdTe/ZnTe interface. The effects of strain, due to hydrostatic and biaxial strain, and the internal electric fields, due to the spontaneous and piezoelectric polarization, are taken into consideration. The dielectric mismatch, through the effective potential, is introduced between the dielectric constants of the dot and the barrier materials. The interband emission energy as a function of dot radius is computed for various Zn alloy content. The optical gain spectra of heavy hole exciton for various Zn concentration are studied. Calculations are obtained for different confinement potentials with the inclusion strain effect. Our results show that (i) the potential taking into account the effects of PB potential due to the dielectric mismatch enhances the exciton binding energy and (ii) the geometry of quantum dot, the strain effects and the Zinc alloy content have great influences on the electrical and optical properties of the dot. Our results are in good agreement with the previous investigators. (author)