SPECTROSCOPIC STUDY OF PIEZOELECTRIC FIELD EFFECTS IN INGAAS GAAS MULTIQUANTUM WELLS GROWN ON (111)B ORIENTED GAAS SUBSTRATES/

An optical study of a series of high quality of piezo-electric (PZ) (1 11)B GaAs-(InGa)As strained multi-quantum wells is reported. Well defi ned DELTAn not-equal 0 transitions (E1HH2, E1HH3 and E2HH1) are observ ed with comparable strength to the DELTAn = 0 transition, as a result of the asymmetric well profile induced by the piezo-electric field. In PLE the onset of the E1HH1 continuum is clearly seen, allowing the de duction of an excition binding energy of 9 meV. Applying a bias to opp ose the PZ field reduces the field in the well, which decreases the qu antum confined Stark shift and weakens the DELTAn not-equal 0 transiti ons. At high bias, corresponding to flat band in the well, strong life time broadening is observed. Good agreement between theory and experim ent is found only by using a value for the PZ constant approximately 3 0% smaller than the commonly accepted value.