Fragile‐to‐Strong Crossover in Supercooled Liquid Ag‐In‐Sb‐Te Studied by Ultrafast Calorimetry

Phase-change random-access memory relies on the reversible crystalline-glassy phase change in chalcogenide thin films. In this application, the speed of crystallization is critical for device performance: there is a need to combine ultrafast crystallization for switching at high temperature with high resistance to crystallization for non-volatile data retention near to room temperature. In phase-change media such as nucleation-dominated Ge2Sb2Te5, these conflicting requirements are met through the highly fragile nature of the temperature dependence of the viscosity of the supercooled liquid. The present study explores, using ultrafast-heating calorimetry, the equivalent temperature dependence for the growth-dominated medium Ag-In-Sb-Te. The crystallization shows (unexpectedly) Arrhenius temperature dependence over a wide intermediate temperature range. Here it is shown that this is evidence for a fragile-to-strong crossover on cooling the liquid. Such a crossover has many consequences for the interpretation and control of phase-change kinetics in chalcogenide media, helping to understand the distinction between nucleation- and growth-dominated crystallization, and offering a route to designing improved device performance.

[1]  T. Grande,et al.  Fragility transition in GeSe2–Se liquids , 2002 .

[2]  Behrad Gholipour,et al.  Ultra-fast calorimetry study of Ge2Sb2Te5 crystallization between dielectric layers , 2012 .

[3]  S. Sen,et al.  Observation of polyamorphism in the phase change alloy Ge1Sb2Te4 , 2012 .

[4]  Y. Tsuchiya.  AC calorimetry of the thermodynamic transition in liquid Ge15Te85 , 1993 .

[5]  Structure of liquid phase change material AgInSbTe from density functional/molecular dynamics simulations , 2009 .

[6]  Mehdi Asheghi,et al.  Ultrafast characterization of phase-change material crystallization properties in the melt-quenched amorphous phase. , 2014, Nano letters.

[7]  A. L. Greer,et al.  Fast and slow crystal growth kinetics in glass-forming melts. , 2014, The Journal of chemical physics.

[8]  Daniele Ielmini,et al.  Evidence for Non-Arrhenius Kinetics of Crystallization in Phase Change Memory Devices , 2013, IEEE Transactions on Electron Devices.

[9]  Matthias Wuttig,et al.  Influence of dielectric capping layers on the crystallization kinetics of Ag5In6Sb59Te30 films , 2004 .

[10]  H. Eugene Stanley,et al.  Transport properties of glass-forming liquids suggest that dynamic crossover temperature is as important as the glass transition temperature , 2010, Proceedings of the National Academy of Sciences.

[11]  C. Angell,et al.  Formation of Glasses from Liquids and Biopolymers , 1995, Science.

[12]  Young-Chang Joo,et al.  The phase-change kinetics of amorphous Ge2Sb2Te5 and device characteristics investigated by thin-film mechanics , 2015 .

[13]  T. Rouxel,et al.  High-temperature elasticity and viscosity of GexSe1−xglasses in the transition range , 2011 .

[14]  Behrad Gholipour,et al.  Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultrafast-heating calorimetry. , 2012, Nature materials.

[15]  Kenneth F. Kelton,et al.  Nucleation in condensed matter : applications in materials and biology , 2010 .

[16]  Matthias Wuttig,et al.  Calorimetric measurements of structural relaxation and glass transition temperatures in sputtered films of amorphous Te alloys used for phase change recording , 2007 .

[17]  Shimeng Yu,et al.  Synaptic electronics: materials, devices and applications , 2013, Nanotechnology.

[18]  Peter H. Poole,et al.  Fragile-to-strong transition and polyamorphism in the energy landscape of liquid silica , 2001, Nature.

[19]  Gary S. Grest,et al.  Liquid-glass transition, a free-volume approach , 1979 .

[20]  Lian Yu,et al.  Crystal growth kinetics exhibit a fragility-dependent decoupling from viscosity. , 2008, The Journal of chemical physics.

[21]  Daniel Krebs,et al.  Crystal growth within a phase change memory cell , 2014, Nature Communications.

[22]  Marco Bernasconi,et al.  Breakdown of Stokes–Einstein relation in the supercooled liquid state of phase change materials , 2012, 1207.7269.

[23]  J. Mauro,et al.  Fragile-to-strong transition in metallic glass-forming liquids. , 2010, The Journal of chemical physics.

[24]  Matthias Wuttig,et al.  Viscosity and elastic constants of thin films of amorphous Te alloys used for optical data storage , 2003 .

[25]  Zhang Chun-zhi,et al.  Fragile-to-Strong Transition in Al-Ni-M (M=La, Pr, Nd) Metallic Glasses , 2010 .

[26]  A. L. Greer,et al.  Kissinger method applied to the crystallization of glass-forming liquids: Regimes revealed by ultra-fast-heating calorimetry , 2015 .

[27]  T. Wágner,et al.  Reversible Amorphous‐to‐Amorphous Transitions in Chalcogenide Films: Correlating Changes in Structure and Optical Properties , 2013 .

[28]  Carl V. Thompson,et al.  On the approximation of the free energy change on crystallization , 1979 .

[29]  Weijie Wang,et al.  Enabling Universal Memory by Overcoming the Contradictory Speed and Stability Nature of Phase-Change Materials , 2012, Scientific Reports.

[30]  C. Angell,et al.  Water II is a "strong" liquid , 1993 .

[31]  Kumar Virwani,et al.  Observation and modeling of polycrystalline grain formation in Ge2Sb2Te5 , 2012 .

[32]  R. Lathe.  Phd by thesis , 1988, Nature.

[33]  P. McMillan,et al.  Structural studies and polymorphism in amorphous solids and liquids at high pressure. , 2006, Chemical Society reviews.

[34]  Y. Yue,et al.  Structural evolution during fragile-to-strong transition in CuZr(Al) glass-forming liquids. , 2015, The Journal of chemical physics.

[35]  G. Adam,et al.  On the Temperature Dependence of Cooperative Relaxation Properties in Glass‐Forming Liquids , 1965 .

[36]  Matthias Wuttig,et al.  Phase-change materials: Fast transformers. , 2012, Nature materials.

[37]  C. Schick,et al.  Fast scanning power compensated differential scanning nano-calorimeter: 2. Heat capacity analysis , 2010 .

[38]  R. Busch,et al.  The influence of shear rate and temperature on the viscosity and fragility of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 metallic-glass-forming liquid , 2007 .

[39]  M. Fontana,et al.  Crystallization process on amorphous GeTeSb samples near to eutectic point Ge15Te85 , 2009 .

[40]  Tobias Van Damme,et al.  Unraveling Crystal Growth in GeSb Phase-Change Films in between the Glass-Transition and Melting Temperatures , 2014 .

[41]  Simone Raoux,et al.  Nanoscale nuclei in phase change materials: Origin of different crystallization mechanisms of Ge2Sb2Te5 and AgInSbTe , 2014 .

[42]  C. Wright,et al.  Beyond von‐Neumann Computing with Nanoscale Phase‐Change Memory Devices , 2013 .

[43]  Matthias Wuttig,et al.  How fragility makes phase-change data storage robust: insights from ab initio simulations , 2014, Scientific Reports.

[44]  W. Hoyer,et al.  The short range order of liquid eutectic AIII-Te and AIV-Te alloys , 1996 .

[45]  Matthias Wuttig,et al.  Calorimetric measurements of phase transformations in thin films of amorphous Te alloys used for optical data storage , 2003 .

[46]  A. L. Greer.  Grain refinement in rapidly solidified alloys , 1991 .

[47]  Matthias Wuttig,et al.  Measurement of crystal growth velocity in a melt-quenched phase-change material , 2013, Nature Communications.

[48]  Guo-Fu Zhou,et al.  Materials aspects in phase change optical recording , 2001 .

[49]  C. Schick,et al.  Fast scanning power compensated differential scanning nano-calorimeter: 1. The device , 2010 .

[50]  John C. Mauro,et al.  Viscosity of glass-forming liquids , 2009, Proceedings of the National Academy of Sciences.

[51]  M. Wuttig,et al.  Atomic force microscopy measurements of crystal nucleation and growth rates in thin films of amorphous Te alloys , 2004 .

[52]  D. Ielmini,et al.  Phase change materials and their application to nonvolatile memories. , 2010, Chemical reviews.