OBSERVATION OF MANY-BODY EFFECTS AND BAND-GAP RENORMALIZATION IN LOW-DIMENSIONAL SYSTEMS WITH BUILT-IN PIEZOELECTRIC FIELDS

We Show that many-body effects and band-gap renormalization can be easily produced in strained-layer quantum wells with internal built-in piezoelectric fields, under photoexcitation. Our observation was made at low temperature by comparing the behavior of Ga0.92In0.08As-GaAs strained-layer quantum wells grown along the (111) and (001) directions and tuning the densities of photoinjected carriers over several decades. Comparison between experimental data and the results of Hartree-calculations including the charge space effects-reveals that many-body interactions are photoinduced.