Digitale Medien
[S.l.]
:
American Institute of Physics (AIP)
Journal of Applied Physics
87 (2000), S. 1034-1041
ISSN:
1089-7550
Quelle:
AIP Digital Archive
Thema:
Physik
Notizen:
Pulsed illumination of lithium–niobate crystals with green light excites electrons from deep traps into the intrinsic defect NbLi5+ (Nb on Li site in the valence state 5+) and creates NbLi4+ centers (small polarons). The electrons trapped in this more shallow center increase the light absorption in the red and near infrared. The dark decay of the polaron concentration is observed by monitoring the relaxation of these absorption changes. Iron-doped lithium–niobate crystals with different concentrations of NbLi are investigated for various illumination conditions and temperatures. The relaxation shows a stretched-exponential behavior which is in disagreement with the predictions of the standard rate-equation-based model. The observed lifetimes of the polarons range from tens of nanoseconds to some milliseconds. Computer simulations reveal that all results can be explained considering distance-dependent excitation and recombination rates, i.e., the lifetime of an individual polaron depends on the distance to the next available deep electron trap. Based on the new insights, tailoring of lithium–niobate crystals for nonvolatile holographic storage becomes possible. © 2000 American Institute of Physics.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.371976
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