Sub-Nanosecond Time-Resolved Structural Measurements of the Phase-Change Alloy Ge2Sb2Te5

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 switching material properties either by laser irradiation or by an electric current 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.