The effect of image potential on electron transmission and electric current in the direct tunneling regime of ultra-thin MOS structures

The direct tunneling current through ultra thin gate dielectrics is modeled by calculating the transmission coefficient of an idealized potential barr ier that is modified by the image force. A numerical solution to the Schrod inger equation shows that the barrier lowering induced by image-potential a ffects the tunneling current largely. An analytical expression for the curr ent is obtained within the Wentel-Kramers-Brillouin approximation. The effe cts of image force on the direct tunneling current are found to increase wi th the applied voltage across oxide (V-ox) and to decrease with the oxide t hickness (T-ox). (C) 2001 Elsevier Science Ltd. All rights reserved.