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Field and temperature effects on the electronic mobility in Alq3 structures
Published online by Cambridge University Press: 22 February 2006
Abstract
Tris(8-hydroxyquinoline) aluminium (Alq3) inserted
in the structure ITO/Alq3/Al is used to show how dielectric spectroscopy and
a $\log \varepsilon '' ={\rm f}(\log \omega)$ representation can separate
dielectric conductivity by bound charges from $\gamma _{0 }$
conductivity
due to residual pseudo free charges. Coupled with the I(V) characteristic, the $\log \varepsilon '' ={\rm f}(\log \omega)$
representation allow to study the
mobility of these carriers as a function of the applied bias voltage V; then
the mobility was estimated to be $\mu \approx 2 \times 10^{-6}$
cm2 V−1 s−1 (with V = 0), and we demonstrate that $\mu $
approximately follows a Poole-Frenkel like law. Consequently, these results
show that mobility determined by field effects is generally overestimated by
around one order of magnitude for an electric field at around 1
MV cm−1. More precisely, we demonstrate that pseudo free charges exhibit a field and weakly temperature dependent mobility, which is in contrast to
carriers involved in the trap–charge limited current regime which exhibit a
temperature dependent and field independent mobility.
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- Research Article
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- © EDP Sciences, 2006
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