Temperature-dependent carrier recombination processes in nanocrystalline Si/SiO2 multilayers studied by continuous-wave and time-resolved photoluminescence

50-period SiO2/SiOx layers have been prepared on Si wafers by ion beam sputtering deposition and subsequently annealed to form Si nanocrystals (NCs) in the SiOx layer. The integrated photoluminescence (PL) intensity of the samples with x < = 1.6 increases on decreasing the temperature down to a certain temperature named as TC, but below TC, it decreases. TC is maintained at 95 K, almost irrespective of x. The rate of decrease of the PL below TC gets slower as x increases up to 1.6, and at x = 1.8, the PL intensity shows a monotonic increase with decreasing temperature. This phenomenon is strongly related to the change in the temperature dependence of the PL decay rate at around TC as x varies. These results can be explained by the fact that the PL behaviours are increasingly influenced by the NCs' environment such as the defect states of the Si NCs/SiO2 interfaces as x increases.