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Band Edge Absorption Saturation Dynamics of Semiconductors
Author(s) -
Kochelap V. A.,
Kulish N. R.,
Lisitsa M. P.,
Malysh N. I.,
Sokolov V. N.
Publication year - 1988
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.2221460134
Subject(s) - photoexcitation , saturation (graph theory) , attenuation coefficient , laser , atomic physics , semiconductor , materials science , absorption (acoustics) , transmission coefficient , absorption edge , optics , molecular physics , transmission (telecommunications) , chemistry , band gap , physics , excited state , optoelectronics , mathematics , electrical engineering , combinatorics , engineering
Temporal evolution of the transmission coefficient and of the output light intensity during the laser pulse is investigated for CdSe single crystals. The nonlinear bleaching observed in the Urbach region of the absorption spectrum at room temperature has a threshold character. With the increase of the laser pulse energy exceeding the threshold value ℰ 1 , the transmission coefficient at first experiences a strong rise and then reaches a saturation. A phenomenological model describing the observed features is proposed assuming an abrupt dependence of the absorption coefficient on the photoexcitation density. The sequence of dynamical relationships between the transmission and the pump level is quantitatively analysed. From experimental data the threshold specific energy and the specific energy required for the bleaching of a 100 μm sample are deduced. They are equal to 2.2 × 10 −11 and 1.9 × 10 −10 J/μm 2 , respectively.