From local structure to nanosecond recrystallization dynamics in AgInSbTe phase-change materials

Phase-change optical memories are based on the astonishingly rapid nanosecond-scale crystallization of nanosized amorphous ‘marks’ in a polycrystalline layer. Models of crystallization exist for the commercially used phase-change alloy Ge 2 Sb 2 Te 5 (GST), but not for the equally important class of...

Full description

Saved in:
Bibliographic Details
Published in:Nature materials 2011-02, Vol.10 (2), p.129-134
Main Authors: Yamada, Noboru, Matsunaga, Toshiyuki, Akola, Jaakko, Kohara, Shinji, Honma, Tetsuo, Kobayashi, Keisuke, Ikenaga, Eiji, Jones, Robert O, Takata, Masaki, Kojima, Rie
Format: Article
Language:English
Subjects:
639/301/119/1000
639/301/930/527
639/638/298/917
Absorption
Alloys
Biomaterials
Chemical bonds
Chemistry and Materials Science
Condensed Matter Physics
Crystallization
Materials Science
Nanotechnology
Optical and Electronic Materials
Phase transitions
Spectroscopy
Spectrum analysis
X-ray diffraction
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Phase-change optical memories are based on the astonishingly rapid nanosecond-scale crystallization of nanosized amorphous ‘marks’ in a polycrystalline layer. Models of crystallization exist for the commercially used phase-change alloy Ge 2 Sb 2 Te 5 (GST), but not for the equally important class of Sb–Te-based alloys. We have combined X-ray diffraction, extended X-ray absorption fine structure and hard X-ray photoelectron spectroscopy experiments with density functional simulations to determine the crystalline and amorphous structures of Ag 3.5 In 3.8 Sb 75.0 Te 17.7 (AIST) and how they differ from GST. The structure of amorphous (a-) AIST shows a range of atomic ring sizes, whereas a-GST shows mainly small rings and cavities. The local environment of Sb in both forms of AIST is a distorted 3+3 octahedron. These structures suggest a bond-interchange model, where a sequence of small displacements of Sb atoms accompanied by interchanges of short and long bonds is the origin of the rapid crystallization of a-AIST. It differs profoundly from crystallization in a-GST. Phase-change materials are key components in rewritable optical disks and are promising for non-volatile electronic memories. The very different structure and ultrafast recrystallization dynamics of another class of phase-change materials, Sb–Te-based alloys, now suggests their use in future memory applications.
ISSN:1476-1122
1476-4660
DOI:10.1038/nmat2931