Digitale Medien
[S.l.]
:
American Institute of Physics (AIP)
Journal of Applied Physics
76 (1994), S. 7367-7371
ISSN:
1089-7550
Quelle:
AIP Digital Archive
Thema:
Physik
Notizen:
The time and temperature dependencies of polarization currents are investigated to higher temperatures and with greater temperature resolution than has been reported previously for zinc oxide varistors. Arrhenius plots of these transient polarization currents yield two thermal activation energies near 140 and 8 meV, which are in reasonable agreement with values reported recently, as well as an additional thermally activated level at 0.66 eV, which becomes evident in the extension of the measurements to T(approximately-greater-than)300 K. Conductance data in this higher temperature range yield the nearly identical energy of 0.68 eV for the intergranular (Schottky) barrier height. The temperature dependence of the exponent m in the power-law expression for the current-time dependence I=I0t−m was carefully examined and found to change twice from 0.5 to 1.0. The nonmonotonic behavior of m(T) can be interpreted as due to resolution of polarization currents from two different traps, each of which evolves from diffusive to dispersive transport as temperature is lowered rather than, for example, a complicated distribution of relaxation times. © 1994 American Institute of Physics.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.357960
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