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Effect of Disorder on Exciton Dynamics in Cation‐Substituted Zn x Cd 1—x S Mixed Crystals
Author(s) -
Shevel S.,
Euteneuer A.,
Hellmann R.,
Göbel E. O.,
Vozny V.,
Vytrykhivsky M.,
Petri W.,
Klingshirn C.
Publication year - 1998
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/(sici)1521-3951(199802)205:2<667::aid-pssb667>3.0.co;2-2
Subject(s) - exciton , quantum tunnelling , luminescence , relaxation (psychology) , impurity , ion , chemistry , crystal (programming language) , condensed matter physics , molecular physics , chemical physics , materials science , physics , optoelectronics , psychology , social psychology , organic chemistry , computer science , programming language
Time‐integrated and time‐resolved (temporal resolution ≈20 ps) excitonic luminescence of cation‐substituted Zn x Cd 1— x S (0 ≤ x ≤ 0.6) platelet mixed crystals has been studied at T = 1.8 K. It is shown that the evolution of exciton spectra with the increase of x is not simply governed by “disorder‐induced broadening” (spread of exciton resonance frequency). Luminescence transients are analyzed to clarify the relative importance of tunneling (usually associated with the localization of excitons by disorder that is known to dominate in the model anion‐substituted system CdSe y S 1— y ). Tunneling in the range of Zn content x ≤ 0.3 is ruled out whereas the indisputable evidences of it (though on a substantially shorter timescale than in CdSe y S 1— y ) are found for the samples with x = 0.34 and 0.41. Both at small and large Zn contents different temporal behavior is observed compared to CdSe y S 1— y implying some persistence of impurity‐bound excitons. It is suggested that in cation‐substituted Zn x Cd 1— x S the inhomogeneously broadened levels of impurity‐bound excitons also participate in the tunneling and relaxation processes whereas the role of disorder‐induced fluctuations of the crystal potential is less important than in anion‐substituted CdSe y S 1— y .