1/f-noise Generated by Constrained Diffusion through a Flux-controlling Boundary

Abstract

Calculations for constrained (one-dimensional) diffusion of current carriers in an external field are made, which concern the spectral density of fluctuations resulting from the relaxation of spatial concentration perturbations. Two different model calculations are presented: First diffusion in an infinite medium. In this case the spectral density of concentration fluctuations shows a 1/f behaviour, but the spectral density of current fluctuations does not. Second the diffusion in a semi-infinite medium is treated. The flux through the boundary (e. g. pore end) is assumed to be pro-portional to the concentration of current carriers at this boundary. In this case concentration as well as current exhibit 1/f behaviour. The results indicate that the existence of flux controlling boundaries (contacts) may be decisive for the occurence of 1/f noise.