Indication of the presence of acceptor states around the Fermi level of amorphous silicon

A junction was grown by sputtering of silicon on a single crystal of high resistivity n-type silicon. The reverese bias V-I characteristics followed Fowler-Nerdheim model with a sudden change in the slope at 0.4 volt indicating an increase in the barrier height. This is attributed to tunneling of extra electrons from the bottom of the conduction band of the substrate to the acceptor traps that face each ether at this bias.