Low-frequency noise probe of interacting charge dynamics in variable-range hopping boron-doped silicon

Low-frequency voltage noise is used to probe stochastic charge dynamics in nonmetallic boron-doped silicon. A ''1/f'' noise spectrum is observed down to 0.1 Hz. The noise magnitude is suppressed and the frequency dependence strengthens at low temperature. The data are inconsistent with single-particle hopping fluctuations, but are compatible with thermally activated rearrangements of configurations involving many charges. Such configurational fluctuations indicate that many-electron excitations an important to charge dynamics in the interacting regime.