Nonohmic Conductivity as a Probe of Crossover from Diffusion to Hopping in Two Dimensions

Abstract

We show that the study of nonlinearity conductivity gives a possibility to determine the condition when the diffusion conductivity changes to the hopping one with increasing disorder. It is experimentally shown that the conductivity of single quantum well GaAs/InGaAs/GaAs heterostructures behaves like diffusive one down to the value approaching (2-3) × 10-2e2/h. © 2004 Elsevier B.V. All rights reserved.