Layered tunnel barriers for nonvolatile memory devices

Fowler-Nordheim tunneling of electrons through "crested" energy barriers (with the height peak in the middle) is much more sensitive to applied voltage than that through barriers of uniform height. Calculations for trilayer barriers, with layer parameters typical for wide-band-gap semiconductors, have shown that by merely doubling the voltage, the tunnel current may be changed by more than 16 orders of magnitude. It is argued that this effect may be used for the implementation of nonvolatile random-access memories combining a few ns cycle time with a few years retention time and for ultradense electrostatic data storage. (C) 1998 American Institute of Physics. [S0003-6951(98)02341-9].