Random walks over a super-percolating two dimensional lattice

Abstract

Two-dimensional networks of ordered quantum dots beyond the percolation threshold are studied, as typical example of conducting nanostructures with quenched random disorder. Theory predicts anomalous diffusion with stretched-exponential relaxation at short distances, and computer simulations on lattices of crossing, straight paths of random length confirm such a behavior. Anomalous diffusion is interpreted as resulting from the higher probability of taking straight, or ballistic paths, when the traveled distance is comparable or shorter than the lattice characteristic length. Diffusion turns over to normal for longer traveled distances, whence all paths tend to become equiprobable. Such random lattice structures represent a model for realistic quantum dot networks, with potential applications in optoelectronics, photovoltaics or spintronics.