Abstract
Femtosecond nonlinear transmission techniques are applied to study mechanisms for optical nonlinearities and ultrafast carrier dynamics in CdS nanocrystals (NC's). The obtained data indicate the change in a dominant hole relaxation channel at high pump levels where nonlinear recombination effects start to play a significant role. This is manifested as a distinct difference in nonlinear-optical responses measured at low and high pump intensities in quasiequilibrium at long times after excitation. The analysis of the wavelength and time dependence of the nonlinear transmission over a wide pump-intensity range shows clearly that this difference is due to an Auger-process-assisted trapping of holes at surface/interface-related states. This trapping leads to efficient charge separation and the generation of a dc electric field that modifies the nonlinear optical response in NC's at high pump intensities.
Original language | English |
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Pages (from-to) | 13173-13179 |
Number of pages | 7 |
Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 55 |
Issue number | 19 |
Publication status | Published - May 15 1997 |
ASJC Scopus subject areas
- Condensed Matter Physics