Crystal Structures of Phase-Change Recording Material, GeTe-Sb2Te3 Pseudo-binary Compounds

Abstract

Crystal structures of the phase-change recording material, GeTe-Sb2Te3, pseudo-binary compounds have been investigated over a decade using synchrotron radiation and the large Debye-Scherrer camera installed at SPring-8’s BL02B2 beamline. These compounds can be crystallized into metastable single phase with NaCl-type structure, for instance, by instantaneous laser irradiation; however, they are transformed into stable phases with long period trigonal structures characterized by the chemical formula, (GeTe)n(Sb2Te3)m (n, m; integer) after sufficient heat treatments. These stable phases can be described as structure with cubic close-packing periodicity (…ABCABC…) where the stacking rules of the Ge/Sb and Te layers are different from each other.