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Self‐trapped excitons on the surface of Si nanocrystals in SiO 2
Author(s) -
Gert Anton,
Yassievich Irina
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201400145
Subject(s) - exciton , nanocrystal , femtosecond , materials science , relaxation (psychology) , silicon , biexciton , excitation , molecular physics , spectroscopy , chemical physics , condensed matter physics , atomic physics , nanotechnology , chemistry , optoelectronics , physics , optics , laser , psychology , social psychology , quantum mechanics
The experimental data recently obtained by the femtosecond pump‐probe spectroscopy technique have shown that the self‐trapped exciton (STE) state plays a key role in the dynamics of hot excitons in photoexcited silicon nanocrystals embedded in a SiO2 matrix. We present a theoretical model of excitons self‐trapped on Si–O bounds at the silicon nanocrystal surface. The thermally activated transition from the STE state to the nanocrystal has been studied. The nonradiative multiphonon recombination of the STE initiated by the interaction with vibrations of local dipoles in a amorphous SiO2 matrix has been considered, too. The relaxation process of “hot” carriers localized in Si nanocrystals has been modulated using Monte Carlo simulation. We have demonstrated that effective exchange between the STE states and “hot” free exciton states opens the new way of the energy relaxation and leads to the wide energy distribution of the hot carriers during 10–100 ps after excitation.