TUNNELLING BETWEEN METALS AND INSULATORS AND ITS ROLE IN CONTACT ELECTRIFICATION

Tunnelling of electrons between a metal and localised states in an insulator is considered, with a view to determining the charge that an insulator can acquire by this mechanism when it is contacted to a metal, and also the extent to which it can lose charge by back-tunnelling during separation. Traps at a single energy are considered primarily, but some attention is given to traps distributed over a range of energy. Back-tunnelling is likely to be significant only at the very highest observed charge densities.