  Two-dimensional electron or hole systems in semiconductors offer the unique
opportunity to investigate the physics of strongly interacting fermions. We
have measured the 1/f resistance noise of two-dimensional hole systems in high
mobility GaAs quantum wells, at densities below that of the metal-insulator
transition (MIT) at zero magnetic field. Two techniques voltage and current
fluctuations were used. The normalized noise power SR/R2 increases strongly
when the hole density or the temperature are decreased. The temperature
dependence is steeper at the lowest densities. This contradicts the predictions
of the modulation approach in the strong localization hopping transport regime.
The hypothesis of a second order phase transition or percolation transition at
a density below that of the MIT is thus reinforced.
