Suppressed shot noise in 1D and 2D electron transport via localised states

We have studied shot noise, SI=F2eI, in the hopping regime of conduction in small-gate 1D and 2D GaAs transistor structures. It is shown that the Fano factor F in 2D hopping is significantly smaller than that in 1D, which we explain by the difference in the structure of the hopping paths. The Fano factor increases with decreasing sample length, but in all cases does not exceed 0.8. We attribute this behaviour to the presence of the electron–electron interaction.