Modulation origin of 1/f noise in two-dimensional hopping

We show that 1 /f noise in a two-dimensional electron gas with hopping conduction can be explained by the modulation of conducting paths by fluctuating occupancy of non-conducting states. The noise is sensitive to the structure of the critical hopping network, which is varied by changing electron concentration, sample size and temperature. With increasing temperature, it clearly reveals the crossover between different hopping regimes.