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Dual action of light in photodarkened Ge–As–S films
Author(s) -
Arsova Darina,
Vateva Elena
Publication year - 2012
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.201147156
Subject(s) - photodarkening , chalcogenide , annealing (glass) , photobleaching , materials science , dual (grammatical number) , chemistry , optics , optoelectronics , physics , fluorescence , composite material , wavelength , fiber laser , art , literature
In annealed chalcogenide films, thinner than 1 µm, highly expressed photodarkening (PD) can be fully restored after prolonged illumination. It was supposed that this light annealing effect (LAE) results from the dual action of light, which provokes not only increase of network disorder at PD but also decrease of disorder leading to photobleaching (PB), competing with PD. To confirm it, the changes of two parameters of disorder are studied: the Tauc slope B 1/2 , dependent on network bonding character, and the Urbach energy E u , associated with tailing of the band edges. It is found that B 1/2 decreases during PD and increases when PB overcomes the PD, which is direct evidence that the basis of the LAE is the dual action of light. The changes of disorder defined by E u are found to be mostly inversely related to the changes of B 1/2 . The peculiarities of this relationship after various treatments are presented and the problem of the correspondence of both parameters of disorder is discussed.