The generation of defects in 3.5nm films was measured as a function of the average electron energy and the total injected fluence. It was found that the generation of defects during electron injection, under both positive and negative bias, led to a positive charge; as deduced from the increase in current for a given bias. Positive charge generation was seen for electrons which were injected into the oxide conduction band; with the generation rate increasing with increasing electron energy. Electrons which traversed the film via direct quantum mechanical tunnelling did not generate measurable numbers of defects. The results were consistent with published results for thicker films, where the defects were attributed to positive charge that was found near to the anode.

D.A.Buchanan, D.J.DiMaria, C.A.Chang, Y.Taur: Applied Physics Letters, 1994, 65[14], 1820-2