Highly doped Si/SiO2/W sandwich structures with an exposed insulator edge: Electrical transport and electroforming

The results are presented of an experimental investigation into electrical transport in Si-SiO2-W sandwich structures with an exposed insulator edge that include highly doped silicon of either conductivity type, the insulator being about 20 nm thick. Processes occurring before, during, or after electroforming are examined. It is demonstrated that electroforming is possible at either voltage polarity. The finding has made it possible to gain a deeper understanding of electrical transport in the structures considered. This is shown to involve ionic transport, minor electroforming, and major electroforming. Minor electroforming is caused by electron emission from the edge of the W electrode when this is negative. Major electroforming is found to be substantially independent of voltage polarity, silicon conductivity type, or doping level. At the same time, certain parameters of I-V characteristics are shown to be determined by the dopant type and concentration when dealing with electroformed structures. © 2007 Pleiades Publishing, Ltd.