High quality surface passivation is of growing importance in the field of photovoltaics because of the continuous improvement of wafer quality. Modulated Photoluminescence (MPL) is a powerful tool that allows to measure the minority carrier lifetime  of semiconductors. An in-house PECVD reactor with in-situ MPL tool  is used to study the evolution of passivating properties during annealing. The measured MPL signal was post-treated in order to take into account two important features. The lifetime calculated from phase shift of the MPL signal is a differential lifetime, from which can be extracted the effective . It also varies with temperature despite the absence of changes in passivation. This dependence is modelled by a power law , so that in the following graph, the equivalent lifetime at 300K is plotted, in order to narrow down observations to changes in passivation properties.