Time-resolved photoluminescence of silicon microstructures fabricated by femtosecond laser in air.

ABSTRACT

Green photoluminescence (PL) from silicon microstructures fabricated by femtosecond laser in air was studied at different temperature by time-resolved spectroscopy. The PL decay profiles are well fitted by a stretched exponential function I(t)=I(0)*exp[-(t/τ)ß]. The dependence of the decay time constant τ and of the stretching index ß on PL photon energy and on the temperature is investigated. A model of transport and recombination of the carriers is introduced as a possible explanation of the stretched exponential decay. The nonradiative recombination rate of the localized carriers, which is dependent on the carrier density and influenced by the trapping site density and the temperature, is deduced to be responsible for this kind of decay.