The effect of imaging forces in ultra thin gate insulator on the tunneling current and its oscillations at the region of transition from the direct tunneling to the Fowler-Nordheim tunneling

The influence of imaging forces on the transparency of the tunnel barrier in the Si-SiO2-Si structures with oxide thickness of a few nanometers was analyzed. It was shown that the substitution of real potential relief with the imaging forces by an effective potential without these forces but with decreased barrier height leads to considerable errors in the transparency. These errors originate from neglecting the real barrier height decrease and the tunneling path reduction with the growth of the applied field. We have calculated the phase of oscillations of the tunneling current in SiO2 layers as a function of the electric field and of the oxide thickness. The theoretical results are in good agreement with experiments. (C) 2003 Elsevier Ltd. All rights reserved.