Phase change materials and their application to random access memory technology

Phase change materials can exist in two different phases, the amorphous and the crystalline phase, which exhibit distinctly different physical properties. It is possible to repeatedly switch the state of these materials, from the amorphous phase to the crystalline phase by heating the material above its crystallization temperature, and from the crystalline to the amorphous phase by melt-quenching. Phase change materials have been utilized very successfully in all modern optical re-writable storage media such as CDs, DVDs and Blu-ray disks. Recently, they have also been applied to solid-state memory devices where their large difference in electrical resistivity is used to store information. This paper reviews the unique properties of phase change materials in particular as they are important for their application to these devices. (C) 2008 Elsevier B.V. All rights reserved.