A nonvolatile memory based on reversible phase changes between fcc and hcp

A nonvolatile memory technology utilizing reversible changes between fcc and hcp crystalline phases is proposed. In this new type of phase-change memory, data are stored in different forms of crystalline phases of (Ge/sub 1/Sb/sub 2/Te/sub 4/)/sub 0.8/(Sn/sub 1/Bi/sub 2/Te/sub 4/)/sub 0.2/ chalcogenide alloy. RESET operation produces the less conductive metastable fcc phase via melt-quenching from the more conductive stable hcp phase and SET operation involves a phase change from fcc directly to hcp. Both RESET and SET operations can be completed as fast as 70 ns with large changes in cell resistance.