Photoluminescence (PL) kinetics of X-xy and X-z excitons at the direct (AlAs-on-GaAs) and inverted (GaAs-on-AlAs) interfaces of asymmetric GaAs/AlAs (1 0 0) type II superlattices (SL) has been investigated. The kinetics of no phonon excitonic recombination is shown to be non-exponential. On the contrary, the kinetics of the phonon replicas follows an exponential law I(t) proportional to exp(-w(ph)t), where w(ph) for the inverted interface is about 1.4 times larger than that for the direct interface. The mean height and lateral size of roughness at the direct and inverted interfaces have been estimated from these data. (C) 2003 Elsevier Science B.V. All rights reserved.