High-pressure induced structural changes in metastable Ge2Sb2Te5 thin films:: An X-ray absorption study

Super-resolution (SR) media offer up to a factor of ten increase in areal storage density over conventional DVD media. Although SR has been realized, there is a strong need for a deeper understanding of structural and electronic changes in Ge2Sb2Te5 (GST), a principal optical memory component, with external perturbations. Recording of SR disks leads to the formation of gas-phase bubbles that in turn lead to the development of large stresses on the underlying GST layer. In this paper we report on XAFS of nominally hydrostatic (0 10 GPa) compressive stress-induced structural changes of the metastable crystalline phase of GST. An analysis showed that the initial splitting of Ge-Te bond lengths of the room-temperature distorted rocksalt structure decreased to a small but finite splitting for p greater than or similar to 6 GPa. The implications of this upon the proposed ferroelectric catastrophe super-RENS readout mechanism are discussed. (c) 2005 Elsevier B.V. All rights reserved.