Built-in electric fields in InAs quantum dots grown on (N11) GaAs substrates

We report on the optical properties and carrier kinetics of a set of InAs self-assembled quantum dots grown on (N11)A/B GaAs substrates by means of cw and time-resolved PL. The cw-PL spectra show a blue shift of the PL band on different (N11) QD structures when increasing the carrier photoinjection. This is attributed to a photoinduced screening of the quantum confined Stark shift of the QD optical transition due to a large built-in electric field. The presence of an internal electric field also induces intrinsic optical non-linearity in time-resolved measurements. The analysis of the recombination kinetics shows that the carrier screening occurs inside the QDs, thus demonstrating the intrinsic nature of the built-in field. The dependence of the internal field on the substrate orientation and termination agrees with the presence of piezoelectric field and permanent dipole moment inside the QDs. (C) 2002 Elsevier Science Ltd. All rights reserved.