OPTICAL STUDIES OF THE PIEZOELECTRIC EFFECT IN (111)-ORIENTED CDTE/CD1-XZNXTE STRAINED QUANTUM-WELLS

We report on the optical properties of (111)-oriented CdTe/Cd1-xZnxTe 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 Cd1-xZnxTe 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/, 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. © 1990 The American Physical Society.