MODEL OF THE POTENTIAL BARRIER OUTSIDE THE SURFACE OF A CONDUCTOR WITH WALLS OF FINITE THICKNESS

Tunneling effect of graphite is studied by atomic force microscopy. The tunneling current in the gap between a conductive tip and a newly cleaved graphite surface at a given voltage keeps almost constant when the gap-distance varies within 1 μm, which cannot be explained by the commonly accepted well model of the potential outside a conductor. Thus modification of the well model is made and a cup model, with a certain wall thickness of the cup, is proposed in the present work.