Optical studies of the piezoelectric effect in (111)-oriented CdTe/Cd1−xZnxTe strained quantum wells

Abstract

We report on the optical properties of (111)-oriented CdTe/${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Zn}}_{\mathit{x}}$Te single quantum wells grown by molecular-beam epitaxy on (001) GaAs substrates. Several quantum wells with different widths were coherently grown on a single, thick ${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Zn}}_{\mathit{x}}$Te buffer layer, which induces the same in-plane strains ≊1% in all quantum wells. A strong red shift of the exciton transition is observed. It increases linearly with the well width at a rate of 2.5 meV/Å, so that exciton transitions occur at energies below the gap of bulk CdTe for wider wells. This linear red shift can only be explained by the existence of a dominant piezoelectric field across the strained quantum wells.