Conductivity of thin nanocrystalline silicon films

It is shown in this paper that thin (200–250 Å) hydrogenated nanocrystalline silicon films have low longitudinal conductivity, comparable to that of undoped amorphous silicon, and high transverse conductivity. These films can be used as doping layers in barrier structures with low surface current leakage. It was found that film conductivity decreases by 8–10 orders of magnitude along the layer as the layer thickness is reduced from 1500 to 200 Å. The observed dependence of the conductivity on thickness can be explained (in terms of percolation theory) by destruction of a percolation cluster made up of nanocrystallites as the layer thickness is decreased.