Low-frequency dielectric properties of Co-Al2O3 composite films

Niklasson, G. A.; Brantervik, K.
April 1987
Applied Physics Letters;4/6/1987, Vol. 50 Issue 14, p937
Academic Journal
We have studied the dielectric permittivity in the frequency range 10-4–102 Hz for Co-Al2O3 cermets with cobalt volume fractions below 0.15. The films were produced by simultaneous electron beam evaporation from two sources. The ac results show an anomalous low-frequency dispersion. We interpret the data in the framework of a random walk on a percolation cluster with traps. A trap distribution parameter, as derived from the ac data, is in qualitative agreement with that derived from current-voltage curves.


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