New conduction and reversible memory phenomena in thin insulating films

Abstract

It has been observed that when thin (200 to 3000 Å) film insulators have been formed by the electrolytic introduction of gold ions from one of the electrodes they can draw appreciable currents. They then show temperature-independent conductivity, voltage-controlled negative resistance and reversible voltage and thermal-voltage memory effects. It is postulated that the injected ions introduce a broad band of localized impurity levels within the normally forbidden band of the insulator. The electrons are assumed to move through the insulator by tunnelling between adjacent sites within the impurity band; it is also assumed that the electrons can, under certain conditions, be trapped within the impurity band. A model based on these ideas accounts in a self-consistent manner for all the experimental observations, and calculations of current-voltage characteristics based on the model are in fact in agree­ment with them.