Intrinsic nonradiative recombination in ensembles of silicon nanocrystals

A detailed time-resolved photoluminescence (TRPL) and continuous wave photoluminescence (CWPL) study as a function of the silicon nanocrystal (Si NC) size and the sample temperature is presented on size-controlled Si NCs fabricated by plasma-enhanced chemical vapor deposition. From the T-dependent TRPL measurements, a model for the radiative as well as for the nonradiative decay processes in Si NCs is established. With the fitting parameters extracted from this model applied to the T-dependent TRPL data, it is possible to reproduce the T-dependent photoluminescence (PL) intensity obtained for different Si NC sizes from CWPL measurements very well. This allows for the description of the PL properties of Si NCs over the whole temperature range and supports correctness of the theoretical assumptions. Furthermore, a detailed discussion on the basis of the theoretical model about the mechanisms behind the nonradiative decay is provided, assuming a temperature activated creation of nonradiative pathways. DOI: 10.1103/PhysRevB.87.035428