Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 20: POSTER A

CPP 20.38: Poster

Montag, 24. März 2003, 19:00–21:00, ZEU/250

Confocal Microscopy on Single Silicon Nanocrystals — •Jörg Martin, Frank Cichos, and Christian von Borczyskowski — Institut für Physik 122501, TU Chemnitz, 09107 Chemnitz

We present experiments on the emission intermittency of single silicon nanocrystals. Silicon nanocrystals are produced by etching porous silicon and subsequent sonification of the porous structure. This leads to isolated particles with a size up to a few ten nanometers. These particle show an emission intermittency, which is observed for other types of semiconductor nanoparticles. The intensity time traces of single particles are governed by short on- and long off periods. The statistics of on and off periods obeys a power law, which is equivalent to a wide distribution of dark states with different trapping time constants. Due to the short on times the transfer to the dark state seems to be rather efficient during the long emission lifetime of silicon. Further we observe a time dependence of the on and off durations. At the beginning of time traces longer on times which saturate to an equilibrium value within a few seconds are found. Along with this, the off times become longer with time and saturate with the same time constant. This leads to an apparent bleaching which is equivalent to what we observe for larger particle ensembles.