Back to Search Start Over

Crystalline GeTe-based phase-change alloys Disorder in order

Authors :
Karthick Perumal
Junji Tominaga
Kiyofumi Nitta
Milos Krbal
Noboru Yamada
Stephen R. Elliott
J. Hegedüs
R. Calarco
Alessandro Giussani
Alexander V. Kolobov
Tomoya Uruga
Toshiyuki Matsunaga
Paul Fons
Source :
Physical Review B. 86(4)
Publication Year :
2012

Abstract

Through the combined use of x-ray absorption and scattering experiments and ab initio simulations, we demonstrate that the metastable cubic phase of GeTe-based phase-change alloys, e.g. ${\mathrm{Ge}}_{2}{\mathrm{Sb}}_{2}{\mathrm{Te}}_{5}$, is significantly more disordered than is generally believed, with a large number of Ge atoms located off octahedral resonantly bonded sites. The stochastic off-octahedral locations of Ge atoms, that are invisible to Bragg diffraction probing the average structure, lead to disruption of the continuous resonance bonding network of the crystalline phase, resulting in localization of charge carriers. It is proposed that the degree of coherency of local rhombohedral displacements, that may be varied, e.g., by doping, can serve as means to control electrical properties of Ge-Sb-Te alloys.

Details

Language :
English
ISSN :
10980121
Volume :
86
Issue :
4
Database :
OpenAIRE
Journal :
Physical Review B
Accession number :
edsair.doi.dedup.....a67a79cefcfb95bdf551fd936c45e9f7
Full Text :
https://doi.org/10.1103/PhysRevB.86.045212