OPTICAL-PROPERTIES OF SINGLE AND DOUBLE (111)-GROWN (GA, IN)AS-GAAS STRAINED-LAYER QUANTUM-WELLS UNDER STRONG PHOTOINJECTION

We show that manybody-effects and bandgap renormalization can be easil y produced in strained-layer quantum wells with internal built-in piez o-electric fields, under photo excitation. Our observation was made at low temperature by comparing the behaviour of Ga0.92In0.08As-GaAs str ained layer single and double quantum wells grown along the (001) and (111) directions when the densities of photoinjected carriers is tuned over several decades. Comparison between experimental data and the re sults of a Hartree calculation including the space charge effects reve als that manybody interactions are efficiently photo-induced in the (1 11)-grown samples. Moreover, in the case of double quantum wells, addi tional transitions appear in the photoluminescence spectra, due to the tunnelling of the two first excited heavy-hole levels for moderate de nsities.