Shot-noise suppression at two-dimensional hopping

We have used Monte Carlo simulation to calculate the shot-noise intensity S_I(ω) at (two-dimensional) hopping using two models: a slanted lattice of localized sites with equal energies and a set of localized sites with random positions and energies. For wide samples we have found a similar dependence of the Fano factor F≡S_I(0)/2eI on the sample length L: F∝L^-α where α=0.85±0.02 and α=0.85±0.07 in uniform and random models, respectively. Moreover, at least for the uniform model, all the data for F as the function of sample length L and width W may be presented via a single function of the ratio W/L^β, with β=2α-1≈0.7. This relation has been interpreted using a simple scaling theory.