High-pressure induced structural changes in metastable GeSbTe thin films; An X-ray absorption study

Fons, P.*; Kolobov, A.*; Tominaga, Junji*; Katayama, Yoshinori

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 GeSbTe (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 6 GPa. The implications of this upon the proposed ferroelectric catastrophe super-RENS readout mechanism are discussed.