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

TL;DR

This paper investigates how nonlinear conductivity measurements can identify the transition from diffusion to hopping conduction in two-dimensional systems, demonstrated through experiments on GaAs/InGaAs/GaAs heterostructures.

Contribution

It introduces a method to detect the crossover from diffusion to hopping conductivity using nonlinearity analysis in two-dimensional materials.

Findings

Conductivity remains diffusive down to ~0.01 e^2/h in GaAs/InGaAs/GaAs heterostructures.

Nonlinear conductivity analysis can serve as a probe for conduction mechanism crossover.

Experimental evidence supports the transition point identification through nonlinearity measurements.

Abstract

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 $10^{-2}e^2/h$.