Abstract
We have studied the resistivity of a two-dimensional electron system in silicon in the temperature range 200 mK <T<7.5 K at zero magnetic field at low electron densities, when the electron system is in the insulating regime. Our results show that at an intermediate temperature range, ρ=exp[(/T] for at least four orders of magnitude up to 3× Ω. This behavior is consistent with the existence of a Coulomb gap. Near the metal/insulator transition, the prefactor was found to be ≊h/, and resistivity scales with temperature. For very low electron densities , the prefactor diminishes with diminishing . A comparison with the theory shows that a specific set of conditions is necessary to observe the behavior of resistivity consistent with the existence of the Coulolmb gap.
- Received 25 May 1995
DOI:https://doi.org/10.1103/PhysRevB.52.7857
©1995 American Physical Society