Advances in nanowire PCM

This chapter is dedicated to the research activities performed on phase change nanowires (NWs) and their potentialities for phase change random access memory (PRAM or PCM) applications. In the first part, the various strategies for scaling down phase change materials to improve device performance are reviewed. Advantages and disadvantages of phase change NWs, topdown and bottom-up fabrication processes, characterization techniques and technological aspects are also discussed. Special focus is placed on the self-assembly of NWs by the vapor-liquid- solid mechanisms, including their compositional and structural analyses. In the second part, the key properties of NW phase change materials and how they affect device performance and reliability are reviewed. Crystallization kinetics, phase transitions, thermal and electrical properties, as well as the properties of core-shell structures, are discussed. Size effects, particularly in relation to scaling parameters, reduction of programming energy and drift resistance are further elaborated, as such effects can influence usefulness of phase changebased PCM devices in addition to discovery of unknown phenomena.