Excess current noise in granular resistors

Excess current noise measurements were carried out on granular resistors and electric contacts. The samples are graphite thick film resistors, metal film resistors, PTC ceramics, ceramic superconductors and crossbar contacts. All noise spectra are of the 1/f type. A one-dimensional model for explaining the 1/f noise in these samples is studied. It is based on the spontaneous temperature fluctuation of the small conducting spots in the samples and thermal conduction in a semi-infinite exponentially tapered solid.