Temperature-induced crossover between bright and dark exciton emission in silicon nanoparticles

The excitonic. ne structure of silicon nanoparticles is investigated by time- resolved and magnetic-.eld-dependent photoluminescence. The results are analyzed using the common model of an excitonic. ne structure consisting of a bright and a dark exciton. We. nd that the radiative recombination rates of both excitons di. er only by a factor of eight. Therefore, we observe a thermal crossover in the character of the emission from bright- exciton- like to dark- exciton- like. The validity of our model is further supported by magnetic-. eld - dependent measurements, in which e. ects of state mixing are observed.