1/f noise in electron glasses -: art. no. 165106

We show that 1/f noise is produced in a three-dimensional electron glass by charge fluctuations due to electron hopping between isolated sites and a percolating network at low-temperatures. The low-frequency noise spectrum goes as omega(-alpha) with alpha slightly larger than 1. This result together with the temperature dependence of alpha and the noise amplitude are in good agreement with the recent experiments. These results hold true both with a flat, noninteracting density of states and with a density of states that includes the Coulomb interactions. In the latter case, the density of states has a Coulomb gap that fills in with increasing temperature. For a large Coulomb gap width, this density of states gives a dc conductivity with a hopping exponent of approximate to0.75 which has been observed in recent experiments. For a small Coulomb gap width, the hopping exponent approximate to0.5.