We present a detailed investigation of the carrier dynamics in a set of InAs/GaAs (N11) quantum dots (QD) by means of time-resolved photoluminesce (PL) techniques. A dynamical red shift of the PL bands when increasing the delay time after the pulse excitation is observed. We attribute this intrinsic optical nonlinearity to the photoinduced screening of internal built-in electric field. The value of the redshift of the QD emission band decays with the carrier population demonstrating the intrinsic nature of the built-in field. Its dependence on the substrate orientation and termination agrees with the expected piezoelectric induced quantum confined Stark effects of the QD optical transitions. © 2001 American Institute of Physics.