Exciton and biexciton recombination in semiconductor nanocrystals

Abstract

The time-resolved photoluminescence of semiconductor nanocrystals was obtained as a function of laser excitation intensity at a low temperature. Exciton and biexciton recombination processes were clearly identified. At laser intensities lower than 3.3×105 W/cm2, only exciton recombination with a lifetime of 4 ns was obtained. At higher laser intensities, biexciton recombination with a lifetime of 1 ns appeared. At laser intensities above 106 W/cm2, recombination of electron-hole plasma occurred with a much shorter lifetime.