We show that the study of conductivity nonlinearity 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 value of order 10−2e2/h.
@article{arxiv.cond-mat/0312118,
title = {Nonohmic conductivity as a probe of crossover from diffusion to hopping in two dimensions},
author = {G. M. Minkov and A. A. Sherstobitov and O. E. Rut and A. V. Germanenko},
journal= {arXiv preprint arXiv:cond-mat/0312118},
year = {2008}
}