In order to assess the effects of nitrogen on GaInNAs during the annealing process, we analyzed several quantum wells (QWs) with different nitrogen contents after annealing at different rapid thermal annealing (RTA) conditions. When only the RTA temperature was varied, we found two blueshift regimes. Up to 700 degrees C (strong blueshift regime), the blueshift experiences a rapid increase with increasing RTA temperature, while above this temperature (weak blueshift regime) it saturates. The activation energies of the blueshift mechanism in the strong blueshift regime decrease with increasing nitrogen content. In the weak blueshift regime, the blueshift saturates more slowly with respect to RTA temperature and to higher values the higher the nitrogen content. When only the RTA time was changed, the blueshift again saturated to higher values the more the nitrogen content. The photoluminescence (PL) efficiency improvement is, on the other hand, unaffected by the nitrogen concentration and depends only on the RTA conditions used. Moreover, short-time annealing at high temperatures results in a smaller PL broadening and is therefore preferable for the growth of active GaInNAs. In outdiffusion from the QW is evident only for long-time annealing. Therefore, the blueshift effects seen for the short-time annealing are related to a different mechanism. (c) 2007 Elsevier B.V. All rights reserved.