Ab Initio Molecular-Dynamics Simulation of Neuromorphic Computing in Phase-Change Memory Materials.

We present an in silico study of the neuromorphic-computing behavior of the prototypical phase-change material, Ge2Sb2Te5, using ab initio molecular-dynamics simulations. Stepwise changes in structural order in response to temperature pulses of varying length and duration are observed, and a good reproduction of the spike-timing-dependent plasticity observed in nanoelectronic synapses is demonstrated. Short above-melting pulses lead to instantaneous loss of structural and chemical order, followed by delayed partial recovery upon structural relaxation. We also investigate the link between structural order and electrical and optical properties. These results pave the way toward a first-principles understanding of phase-change physics beyond binary switching.

[1]  H.-S. Philip Wong,et al.  Energy efficient programming of nanoelectronic synaptic devices for large-scale implementation of associative and temporal sequence learning , 2011, 2011 International Electron Devices Meeting.

[2]  Hafner,et al.  Ab initio molecular dynamics for liquid metals. , 1995, Physical review. B, Condensed matter.

[3]  S. Elliott,et al.  Microscopic origin of the fast crystallization ability of Ge-Sb-Te phase-change memory materials. , 2008, Nature materials.

[4]  Germany,et al.  Neural network interatomic potential for the phase change material GeTe , 2012, 1201.2026.

[5]  G. W. Burr,et al.  Experimental demonstration and tolerancing of a large-scale neural network (165,000 synapses), using phase-change memory as the synaptic weight element , 2015, 2014 IEEE International Electron Devices Meeting.

[6]  Charles M. Lieber,et al.  Nanoelectronics from the bottom up. , 2007, Nature materials.

[7]  Shimeng Yu,et al.  A Low Energy Oxide‐Based Electronic Synaptic Device for Neuromorphic Visual Systems with Tolerance to Device Variation , 2013, Advanced materials.

[8]  F. Attneave,et al.  The Organization of Behavior: A Neuropsychological Theory , 1949 .

[9]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[10]  Olivier Bichler,et al.  Phase change memory as synapse for ultra-dense neuromorphic systems: Application to complex visual pattern extraction , 2011, 2011 International Electron Devices Meeting.

[11]  H. Markram,et al.  Regulation of Synaptic Efficacy by Coincidence of Postsynaptic APs and EPSPs , 1997, Science.

[12]  Desmond Loke,et al.  Understanding the multistate SET process in Ge-Sb-Te-based phase-change memory , 2012 .

[13]  J. Knott.  The organization of behavior: A neuropsychological theory , 1951 .

[14]  Blöchl,et al.  Projector augmented-wave method. , 1994, Physical review. B, Condensed matter.

[15]  Wei Yang Lu,et al.  Nanoscale memristor device as synapse in neuromorphic systems. , 2010, Nano letters.

[16]  M. Kund,et al.  Nanosecond switching in GeTe phase change memory cells , 2009 .

[17]  Damien Querlioz,et al.  Probabilistic neuromorphic system using binary phase-change memory (PCM) synapses: Detailed power consumption analysis , 2013, 2013 13th IEEE International Conference on Nanotechnology (IEEE-NANO 2013).

[18]  W. Regehr,et al.  Short-term synaptic plasticity. , 2002, Annual review of physiology.

[19]  H. Berendsen,et al.  Molecular dynamics with coupling to an external bath , 1984 .

[20]  W. J. Wang,et al.  Breaking the Speed Limits of Phase-Change Memory , 2012, Science.

[21]  S. Elliott,et al.  Ab Initio computer simulation of the early stages of crystallization: application to Ge(2)Sb(2)Te(5) phase-change materials. , 2011, Physical review letters.

[22]  B. DeSalvo,et al.  Phase Change Memory and Chalcogenide Materials for Neuromorphic Applications: Emphasis on Synaptic Plasticity , 2012 .

[23]  Rong Zhao,et al.  Ultrafast phase-change logic device driven by melting processes , 2014, Proceedings of the National Academy of Sciences.

[24]  Structural insights into the formation and evolution of amorphous phase‐change materials , 2013 .

[25]  Eric Pop,et al.  Low-Power Switching of Phase-Change Materials with Carbon Nanotube Electrodes , 2011, Science.

[26]  D. Ielmini,et al.  Logic Computation in Phase Change Materials by Threshold and Memory Switching , 2013, Advanced materials.

[27]  M. Bear,et al.  A biophysically-based neuromorphic model of spike rate- and timing-dependent plasticity , 2011, Proceedings of the National Academy of Sciences.

[28]  K Schulten,et al.  VMD: visual molecular dynamics. , 1996, Journal of molecular graphics.

[29]  H. Monkhorst,et al.  SPECIAL POINTS FOR BRILLOUIN-ZONE INTEGRATIONS , 1976 .

[30]  D. Loke,et al.  Guest‐Cage Atomic Interactions in a Clathrate‐Based Phase‐Change Material , 2014, Advanced materials.

[31]  Vogl,et al.  Generalized Kohn-Sham schemes and the band-gap problem. , 1996, Physical review. B, Condensed matter.

[32]  Shimeng Yu,et al.  Low-Energy Robust Neuromorphic Computation Using Synaptic Devices , 2012, IEEE Transactions on Electron Devices.

[33]  G. Bi,et al.  Synaptic Modifications in Cultured Hippocampal Neurons: Dependence on Spike Timing, Synaptic Strength, and Postsynaptic Cell Type , 1998, The Journal of Neuroscience.

[34]  R. O. Jones,et al.  Nucleus-driven crystallization of amorphous Ge2Sb2Te5: A density functional study , 2012 .

[35]  Byoungil Lee,et al.  Nanoelectronic programmable synapses based on phase change materials for brain-inspired computing. , 2012, Nano letters.

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