SPring-8, the large synchrotron radiation facility

Date: 13:30～14:30, December 19, 2006

Place: Public Relations Center, SPring-8

Speaker: Paul Fons, National Institute of Advanced Industrial Science and Technology (AIST)

Title: Taking snapshots of the switching process: using time-resolved XAFS to see transitions in the phase-change memory alloy Ge₂Sb₂Te₅

Abstract:
     Phase-change alloys constitute the basis for a widening collection of storage technologies both optical and electrical. These uses of phase-change alloys are characterized by reversible switching between amorphous and crystalline phases either by laser irradiation or by an electric current; the resulting changes in material properties can be used for non-volitile data storage. Switching typically occurs on the nanosecond time scale. Considering the conflicting requirements for high-speed switching, yet long term data storage integrity, a deeper understanding of the switching processes in these materials is essential for insightful application development. We have used synchrotron-based time-resolved x-ray absorption fine structure spectroscopy (XAFS), a technique equally suitable for amorphous and crystalline phases to elaborate details in structural changes in the phase-change process on a sub-nanosecond time scale using optical pump/x-ray probe techniques. In this work, we present initial results of sub-nanosecond laser excitation of the laser-reamorphized state of Ge₂Sb₂Te₅. The technique is general and can be applied to a wide variety of nanoscale structures. Preliminary results taken at the Advanced Photon Source as well as recent experiments taken at SPring-8 will be discussed.

Organizer: Motohiro SUZUKI (phs 3871)