PIEZOELECTRIC-FIELD EFFECTS ON TRANSITION ENERGIES, OSCILLATOR-STRENGTHS, AND LEVEL WIDTHS IN (111)B-GROWN (IN,GA)AS/GAAS MULTIPLE-QUANTUM WELLS

We report a spectroscopic study of high-quality piezoelectric (PZ) (111)B GaAs/(In,Ga)As strained multiple quantum wells. Normally forbidden DELTAn not-equal 0 transitions (E1HH2, E1HH3, E2HH1) are observed strongly due to the asymmetric well profile induced by the PZ field. Applying a bias to oppose the PZ field reduces the quantum-confined Stark shifts and weakens the DELTAn not-equal 0 transitions. At high bias, corresponding to flat band in the well, strong lifetime broadening is observed. Good agreement between theory and experiment is found, but only by using a value for the PZ constant approximately 30% smaller than the commonly accepted value.