Field-dependant hopping conduction in silicon nanocrystal films

We investigate the electric field dependence of hopping conduction in 300 nm thick films of similar to 8 nm diameter silicon nanocrystals. The hopping conductivity sigma follows a ln(sigma)proportional to 1/T-1/2 dependence with temperature T, explained by a percolation hopping conduction model. At high fields F>similar to 1x10(5) V/cm, the hopping conductivity follows a ln(sigma)proportional to F-1/2 dependence. This dependence is investigated using the concept of effective temperature, introduced originally by Shklovskii for hopping conduction in disordered materials.