Nonohmic conductivity as a probe of crossover from diffusion to hopping in two dimensions

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 View the MathML source