skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Competing covalent and ionic bonding in Ge-Sb-Te phase change materials

Journal Article · · Scientific Reports
DOI:https://doi.org/10.1038/srep25981· OSTI ID:1254095
 [1];  [2];  [3];  [4];  [5]
  1. Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany)
  2. FAMU-FSU College of Engineering, Tallahassee, FL (United States)
  3. Univ. of Missouri, Columbia, MO (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); FAMU-FSU College of Engineering, Tallahassee, FL (United States)

Ge2Sb2Te5 and related phase change materials are highly unusual in that they can be readily transformed between amorphous and crystalline states using very fast melt, quench, anneal cycles, although the resulting states are extremely long lived at ambient temperature. These states have remarkably different physical properties including very different optical constants in the visible in strong contrast to common glass formers such as silicates or phosphates. This behavior has been described in terms of resonant bonding, but puzzles remain, particularly regarding different physical properties of crystalline and amorphous phases. Here we show that there is a strong competition between ionic and covalent bonding in cubic phase providing a link between the chemical basis of phase change memory property and origins of giant responses of piezoelectric materials (PbTiO3, BiFeO3). This has important consequences for dynamical behavior in particular leading to a simultaneous hardening of acoustic modes and softening of high frequency optic modes in crystalline phase relative to amorphous. As a result, this different bonding in amorphous and crystalline phases provides a direct explanation for different physical properties and understanding of the combination of long time stability and rapid switching and may be useful in finding new phase change compositions with superior properties.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Energy Frontier Research Centers (EFRC) (United States). Solid-State Solar-Thermal Energy Conversion Center (S3TEC)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC05-00OR22725; SC0001299; FG02-09ER46577
OSTI ID:
1254095
Journal Information:
Scientific Reports, Vol. 6, Issue C; ISSN 2045-2322
Publisher:
Nature Publishing GroupCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 31 works
Citation information provided by
Web of Science

References (59)

Ab Initio Computer Simulation of the Early Stages of Crystallization: Application to Ge 2 Sb 2 Te 5 Phase-Change Materials journal September 2011
Resonant bonding in crystalline phase-change materials journal July 2008
Unravelling the interplay of local structure and physical properties in phase-change materials journal December 2005
Reversible Electrical Switching Phenomena in Disordered Structures journal November 1968
A possible mechanism of ultrafast amorphization in phase-change memory alloys: an ion slingshot from the crystalline to amorphous position journal October 2007
Ultrafast time-resolved electron diffraction revealing the nonthermal dynamics of near-UV photoexcitation-induced amorphization in Ge2Sb2Te5 journal August 2015
Structural basis for the fast phase change of Ge2Sb2Te5: Ring statistics analogy between the crystal and amorphous states journal November 2006
Microscopic origin of the fast crystallization ability of Ge–Sb–Te phase-change memory materials journal March 2008
Breaking the Speed Limits of Phase-Change Memory journal June 2012
Erratum: Phase-change materials for rewriteable data storage journal November 2007
Towards a universal memory? journal April 2005
Impact of vacancy ordering on thermal transport in crystalline phase-change materials journal December 2014
Electrical Wind Force-Driven and Dislocation-Templated Amorphization in Phase-Change Nanowires journal June 2012
Electrons in disordered structures journal January 1967
Understanding the phase-change mechanism of rewritable optical media journal September 2004
Effects of Resonance Bonding on the Properties of Crystalline and Amorphous Semiconductors journal July 1973
Distortion-triggered loss of long-range order in solids with bonding energy hierarchy journal March 2011
Pressure-induced reversible amorphization and an amorphous-amorphous transition in Ge2Sb2Te5 phase-change memory material journal June 2011
Large displacement of germanium atoms in crystalline Ge2Sb2Te5 journal February 2005
Epitaxial films for Ge–Sb–Te phase change memory journal March 2009
The crystal structure of IV-VI compounds. I. Classification and description journal September 1980
Optical properties of pseudobinary GeTe, Ge 2 Sb 2 Te 5 , GeSb 2 Te 4 , GeSb 4 Te 7 , and Sb 2 Te 3 from ellipsometry and density functional theory journal September 2009
Insights into the structure of the stable and metastable ( GeTe ) m ( Sb 2 Te 3 ) n compounds journal December 2008
ELF: The Electron Localization Function journal September 1997
Interfacial phase-change memory journal July 2011
Effective coordination numbers (ECoN) and mean Active fictive ionic radii (MEFIR) [1,2] * journal January 1979
Resonant bonding leads to low lattice thermal conductivity journal April 2014
Microstructural and vibrational properties of PVT grown Sb2Te3 crystals journal January 2014
Prospects of Doped Sb–Te Phase-Change Materials for High-Speed Recording
  • Lankhorst, Martijn H. R.; Pieterson, Liesbeth van; Schijndel, Mark van
  • Japanese Journal of Applied Physics, Vol. 42, Issue Part 1, No. 2B https://doi.org/10.1143/JJAP.42.863
journal February 2003
Structural phase transitions on the nanoscale: The crucial pattern in the phase-change materials Ge 2 Sb 2 Te 5 and GeTe journal December 2007
Application of Bond Constraint Theory to the Switchable Optical Memory Material Ge 2 Sb 2 Te 5 journal June 2006
Phase-Change Materials: Vibrational Softening upon Crystallization and Its Impact on Thermal Properties journal April 2011
Thermal conductivity of phase-change material Ge2Sb2Te5 journal October 2006
Optical properties of cubic and rhombohedral GeTe journal May 2013
Origin of ferroelectricity in perovskite oxides journal July 1992
Dynamical atomic charges: The case of AB O 3 compounds journal September 1998
Giant LO-TO splittings in perovskite ferroelectrics journal May 1994
Infrared-Absorption Studies on Barium Titanate and Related Materials journal March 1957
Apparent Ionic Charges and Vibrational Eigenmodes of BaTi O 3 and Other Perovskites journal May 1967
Enhanced Born charge and proximity to ferroelectricity in thallium halides journal April 2010
The chain structure of BaTiO3 and KNbO3 journal October 1968
First-Principles Determination of Chain-Structure Instability in KNb O 3 journal May 1995
Relationship between local structure and phase transitions of a disordered solid solution journal October 2002
Reinterpretation of the bond-valence model with bond-order formalism: An improved bond-valence-based interatomic potential for PbTiO 3 journal September 2013
Electron diffraction and high-resolution transmission electron microscopy of the high temperature crystal structures of GexSb2Te3+x (x=1,2,3) phase change material journal October 2002
From ultrasoft pseudopotentials to the projector augmented-wave method journal January 1999
Generalized Gradient Approximation Made Simple journal October 1996
Generalized Gradient Approximation Made Simple [Phys. Rev. Lett. 77, 3865 (1996)] journal February 1997
Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set journal October 1996
Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set journal July 1996
First-principles calculations of the ferroelastic transition between rutile-type and CaCl 2 -type SiO 2 at high pressures journal October 2008
Special quasirandom structures journal July 1990
Electronic structure calculations of solids using the WIEN2k package for material sciences journal August 2002
Investigation of the optical and electronic properties of Ge2Sb2Te5 phase change material in its amorphous, cubic, and hexagonal phases journal May 2005
Optical properties of Ge:Sb:Te ternary alloys
  • Garcı́a-Garcı́a, E.; Mendoza-Galván, A.; Vorobiev, Y.
  • Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, Vol. 17, Issue 4 https://doi.org/10.1116/1.581894
journal July 1999
Optical contrast and laser-induced phase transition in GeCu 2 Te 3 thin film journal February 2013
Localization Patterns in Interstitial Space: A Special Property of the Electron Localization Function (ELF) journal June 1997
Low-cost and nanoscale non-volatile memory concept for future silicon chips journal March 2005
First-Principles Determination of Chain-Structure Instability in KNbO$_3$ text January 1994

Cited By (8)

Structure and Properties of Chalcogenide Materials for PCM book November 2017
Revealing the intrinsic nature of the mid-gap defects in amorphous Ge2Sb2Te5 journal July 2019
Nonequilibrium ab initio molecular-dynamics simulations of lattice thermal conductivity in irradiated glassy Ge 2 Sb 2 Te 5 journal January 2020
Bonding in phase change materials: concepts and misconceptions journal March 2018
Atomic-scale structure of the glassy Ge 2 Sb 2 Te 5 phase change material: A quantitative assessment via first-principles molecular dynamics journal December 2017
Dielectric properties of amorphous phase-change materials text January 2017
Reversible optical tuning of GeSbTe phase-change metasurface spectral filters for mid-wave infrared imaging. text January 2020
Revealing the intrinsic nature of the mid-gap defects in amorphous Ge2Sb2Te5. text January 2019