This title appears in the Scientific Report :
2011
Please use the identifier:
http://dx.doi.org/10.1103/PhysRevB.83.094113 in citations.
Please use the identifier: http://hdl.handle.net/2128/10942 in citations.
Polymorphism in phase-change materials: melt-quenched and as-deposited amorphous structures in Ge_2 Sb_2 Te_5 from density functional calculations
Polymorphism in phase-change materials: melt-quenched and as-deposited amorphous structures in Ge_2 Sb_2 Te_5 from density functional calculations
The as-deposited (AD) amorphous structure of the prototype phase change material Ge2Sb2Te5 (GST-225) has been studied by density functional calculations for a 648-atom sample generated by computer-aided deposition at 300 K. The AD sample differs from a melt-quenched (MQ) sample in essential ways: (1...
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Personal Name(s): | Akola, J. |
---|---|
Larrucea, J. / Jones, R. O. | |
Contributing Institute: |
Quanten-Theorie der Materialien; PGI-1 |
Published in: | Physical Review B Physical review / B, 83 83 (2011 2011) 9 9, S. 094113 094113 |
Imprint: |
College Park, Md.
APS
2011
|
Physical Description: |
094113 |
DOI: |
10.1103/PhysRevB.83.094113 |
Document Type: |
Journal Article |
Research Program: |
Grundlagen für zukünftige Informationstechnologien |
Series Title: |
Physical Review B
83 |
Subject (ZB): | |
Link: |
Get full text OpenAccess OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://hdl.handle.net/2128/10942 in citations.
The as-deposited (AD) amorphous structure of the prototype phase change material Ge2Sb2Te5 (GST-225) has been studied by density functional calculations for a 648-atom sample generated by computer-aided deposition at 300 K. The AD sample differs from a melt-quenched (MQ) sample in essential ways: (1) Ge atoms are predominantly tetrahedrally coordinated, and (2) homopolar and Ge-Sb bonds are more common and reduce the number of ABAB squares (A = Ge, Sb; B = Te), the characteristic building blocks of the material. The first observation resolves the contradiction between measured (EXAFS) and calculated Ge-Te bond lengths, and the latter explains the very different crystallization speeds. Sb and Te have higher chemical coordination than suggested by the "8-N rule" of covalent networks (N is the number of valence electrons). The EXAFS signal calculated for AD agrees much better with experiment than that calculated for MQ. |