Publications
Publications and papers from the nano memory resistors project team
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Live Demonstration: an Embedded Environmental Control Micro-Chamber System for RRAM Memristor Characterisation
Authors:
  T. Abbey, A. Serb, A. Khiat, N. Vasilakis, L. Michalas, S. Stathopoulos, and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2018.

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An Embedded Environmental Control Micro-Chamber System for RRAM Memristor Characterisation
Authors:
  T. Abbey, A. Serb, A. Khiat, N. Vasilakis, L. Michalas, S. Stathopoulos, and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2018.

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Live Demonstration: Benchmarking Analogue Performance of Emerging Random Access Memory Technologies
Authors:
  S. Stathopoulos, A. Khiat, A. Serb, and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2018.

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Benchmarking Analogue Performance of Emerging Random Access Memory Technologies
Authors:
  S. Stathopoulos, A. Khiat, A. Serb, and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2018.

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Metal Oxide-Enabled Reconfigurable Memristive Threshold Logic Gates
Authors:
  G. Papandroulidakis, A. Khiat, A. Serb, S. Stathopoulos, L. Michalas, and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2018.

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Processing Big-Data with Memristive Technologies: Splitting the Hyperplane Efficiently
Authors:
  A. Serb, G. Papandroulidakis, A. Khiat, and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2018.

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High-Sensitivity memristor-baesd Threshold Detection
Authors:
  A. Serb, and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2018.

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Brain and silicon neurons networked by memristive synapses
Authors:
  A. Serb, A. Corna, R. George, A. Khiat, F. Rocchi, M. Reato, M. Maschietto, C. Mayr, G. Indiveri, S. Vassanelli, and T. Prodromakis. Nature, under review.

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Interface barriers at Metal – TiO2 contacts
Authors:
  L. Michalas, A. Khiat, S. Stathopoulos, T. Prodromakis. IEEE Trans. Scientific Reports, under review.

The electrical properties of thin TiO2 films have recently been extensively exploited towards enabling a variety of metal-oxide electron devices: unipolar/bipolar semiconductor devices and/or memristors.

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Impact and constrains of volatile selectors on ReRAM crossbar operation
Authors:
  S. Cortese, I. Messaris, A. Khiat, A. Serb, and T. Prodromakis. IEEE Trans. Nanotechnology, under review.

Volatile switching selectors are considered an emerging class of selector technology for ReRAM crossbar arrays. Their fast turn on, low current baseline and high current density make them a competitive solution for achieving sneak-free crossbars.

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Spike Sorting using non-volatile metal-oxide memristor
Authors:
  I. Gupta, A. Serb, A. Khiat, M. Trapatseli, and T. Prodromakis. Scientific Reports, under review.

Electrophysiological techniques have improved substantially over the past years to the point that neuroprosthetics applications are becoming viable.

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Practical Demonstration of a Memristive Fuse
Authors:
  A. Serb, A. Khiat, and T. Prodromakis. Scientific Reports, in press.

Since its inception the memristive fuse has been a good example of how small numbers of memristors can be combined to obtain useful behaviours unachievable by individual devices.

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Emulating long-term synaptic dynamics with memristive devices
Authors:
  S. L. Wei, E. Vasilaki, A. Khiat, I. Salaoru, R. Berdan, and T. Prodromakis. Frontiers in Neuromorphic Eng., in press.

The potential of memristive devices is often seeing in implementing neuromorphic architectures for achieving brain-like computation.

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Sub 100 nW volatile nano-metal-oxide memristor as synaptic like encoder of neuronal spike
Authors:
  I. Gupta, A. Serb, A. Khiat, R. Zeitler, S. Vassanelli, and T. Prodromakis. IEEE TBCAS, in press.

Advanced neural interfaces mediate a bio-electronic link between the nervous system and microelectronic devices, bearing great potential as innovative therapy for various diseases.

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A Data-Driven Verilog-A ReRAM Model
Authors:
  I. Messaris, A. Serb, S. Stathopoulos, A. Khiat, S. Nikolaidis, and T. Prodromakis. IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, Volume: PP, Issue: 99, 2018

The translation of emerging application concepts that exploit Resistive Random Access Memory (ReRAM) into large-scale practical systems requires realistic yet computationally efficient device models.

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Interface Asymmetry Induced by Symmetric Electrodes on Metal-Al:TiOx-Metal Structures
Authors:
  L. Michalas, M. Trapatseli, S. Stathopoulos, S. Cortese, A. Khiat and T. Prodromakis. IEEE Transactions on Nanotechnology, Volume: PP, Issue: 99, 2017.

Emerging memory technologies have sparked great interest in studying a variety of materials that can be employed in Metal-Insulator-Metal topologies to support resistive switching.

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Multibit memory operation of metal-oxide bi-layer memristors
Authors:
  Spyros Stathopoulos, Ali Khiat, Maria Trapatseli, Simone Cortese, Alexantrou Serb, Ilia Valov, and Themis Prodromakis. Scientific Reports, vol. 7, 17532, 2017.

Emerging nanoionic memristive devices are considered as the memory technology of the future and have been winning a great deal of attention due to their ability to perform fast and at the expense of low-power and -space requirements.

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Introducing the nanoworld
Authors:
  Themis Prodromakis. Nature Nanotechnology, vol. 12, 832, 2017.

Lectures are probably the oldest form of science outreach, dating back to the 1820s when Faraday organized the first of the Royal Institution's Christmas Lectures (http://www.rigb.org/christmas-lectures).

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Correlated resistive/capacitive state variability in solid TiO2 based memory device
Authors:
  Qingjiang Li, Iulia Salaoru, Ali Khiat, Hui Xu, and Themistoklis Prodromakis. Appl. Phys. A (2017) 123:372 DOI 10.1007/s00339-017-0991-5

In this work, we experimentally demonstrated the correlated resistive/capacitive switching and state variability in practical TiO2 based memory devices.

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Impact of ultra-thin Al2O3-y layers on TiO2-x ReRAM switching characteristics
Authors:
  Maria Trapatseli, Simone Cortese, Alexander Serb, Ali Khiat, and Themistoklis Prodromakis. Journal of Applied Physics 121, 184505 (2017).

Transition metal-oxide resistive random access memory devices have demonstrated excellent performance in switching speed, versatility of switching and low-power operation.

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Volatility Characterisation for RRAM device
Authors:
  I. Gupta, A. Serb, R. Berdan, A. Khiat, and T. Prodromakis. IEEE Electron Device letters, vol. 38, no. 1, 2017.

Emerging technologies, such as resistive random access memory (RRAM), are being actively researched for its potential applications in developing new technologies inspired by brainlike neuromorphic computing.

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Improving detection accuracy of memristor-based bio-signal sensing platform
Authors:
  I. Gupta, A. Serb, A. Khiat, and T. Prodromakis. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, VOL. 11, NO. 1, FEBRUARY 2017

Recently a novel neuronal activity sensor exploiting the intrinsic thresholded integrator capabilities of memristor devices has been proposed.

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A Memristor-CMOS Hybrid Architecture Concept for on-Line Template Matching
Authors:
  A. Serb, C. Papavassiliou and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2017.

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ReMem: a system for accessing memristors remotely over the internet
Authors:
  A. Zekovic, A. Serb and T. Prodromakis. 2017 Stephen and Sharon Seiden Frontiers in Engineering and Science Workshop: Beyond CMOS: From Devices to Systems, June 2017.

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Hardware-Level Bayesian Inference
Authors:
  A. Serb, E. Manino, I. Messaris, L. Tran-Thanh and T. Prodromakis. 31st Conference on Neural Information Processing Systems (NIPS), 2017.

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The use of dielectric barrier layers for multibit operation in TiOx- based memristors
Authors:
  S24. S. Stathopoulos, A. Khiat, M. Trapatseli, S. Cortese, A. Serb, and T. Prodromakis. International Conference on Memristive Materials, Devices & Systems, April 2017.

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Unsupervised learning in probabilistic neural networks with multi-state MOx memristive synapses
Authors:
  S23. A. Serb, J. Bill, A. Khiat, R. Berdan, R. Legenstein, and T. Prodromakis. International Conference on Memristive Materials, Devices & Systems, April 2017.

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Memristive-based Reconfigurable Analogue Blocks
Authors:
  S22. C. A. Angeles Ruiz, A. Serb, A. Khiat, C. Papavassiliou, and T. Prodromakis. International Conference on Memristive Materials, Devices & Systems, April 2017.

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Pt/TiOx/Pt Resistive switching devices for flexible applications
Authors:
  S21. A. Khiat, S. Cortese, A. Serb, and T. Prodromakis. International Conference on Memristive Materials, Devices & Systems, April 2017.

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Memristor-based Spike Sorting platform
Authors:
  S20. I. Gupta, A. Serb, A. Khiat, and T. Prodromakis. International Conference on Memristive Materials, Devices & Systems, April 2017.

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A compact Verilog-A ReRAM model
Authors:
  S19. I. Messaris, A. Serb, A. Khiat, S. Nikolaidis, and T. Prodromakis. International Conference on Memristive Materials, Devices & Systems, April 2017.

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Impact of Volatile Switching Selector on ReRAM crossbar readout operations
Authors:
  S18. S. Cortese, I. Messaris, A. Khiat, and T. Prodromakis. International Conference on Memristive Materials, Devices & Systems, April 2017.

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Sub-15 nm High Density Crossbar Memristive Devices
Authors:
  S17. A. Khiat, P. Ayliffe, and T. Prodromakis. International Conference on Memristive Materials, Devices & Systems, April 2017.

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A TiO2 ReRAM Parameter Extraction Method
Authors:
  S16. I. Messaris, S. Nikolaidis, A. Serb, S. Stathopoulos, I. Gupta, A. Khiat, and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2017.

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Live Demonstration: a TiO2 ReRAM Parameter Extraction Method
Authors:
  S15. I. Messaris, S. Nikolaidis, A. Serb, S. Stathopoulos, I. Gupta, A. Khiat, and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2017.

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Live Demonstration: mNET: a Visually Rich Memristor Crossbar Simulator
Authors:
  S14. R. Berdan, A. Serb, C. Papavassiliou and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2017.

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Mitigating Noise Effects in Volatile Nano-Metal Oxide Neural Detector
Authors:
  S13. I. Gupta, A. Serb, A. Khiat, and T. Prodromakis. Proceedings of the IEEE International Symposium on Circuits and Systems, May 2017.

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Sub 100nW volatile nano-metal-oxide memristor as synaptic-like encoder of neuronal spikes
Authors:
  Gupta, A. Serb, A. Khiat, R. Zeitler, S. Vassanelli, and T. Prodromakis. arXiv:1611.09671, Nov 2016

Advanced neural interfaces mediate a bio-electronic link between the nervous system and microelectronic devices, bearing great potential as innovative therapy for various diseases.

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Practical Demonstration of a Memristive Fuse
Authors:
  J93. A. Serb, A. Khiat and T. Prodromakis. arXiv:1609.02410, Sep 2016.

Since its inception the memristive fuse has been a good example of how small numbers of memristors can be combined to obtain useful behaviours unachievable by individual devices.

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Analog Memristive Synapse in Spiking Networks Implementing Unsupervised Learning
Authors:
  E. Covi, S. Brivio, A. Serb, T. Prodromakis, M. Fanciulli, and S. Spiga. Front Neurosci. 10: 482, 2016.

Emerging brain-inspired architectures call for devices that can emulate the functionality of biological synapses in order to implement new efficient computational schemes able to solve ill-posed problems.

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Experimental study of gradual/abrupt dynamics of HfO2-based memristive devices
Authors:
  S. Brivio, E. Covi, A. Serb, T. Prodromakis, M. Fanciulli, and S. Spiga. Appl. Phys. Lett. 109, 133504, 2016.

The resistance switching dynamics of TiN/HfO2/Pt devices is analyzed in this paper. When biased with a voltage ramp of appropriate polarity, the devices experience SET transitions from high to low resistance states in an abrupt manner, which allows identifying a threshold voltage.

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Resistive switching of Pt/TiOx/Pt devices fabricated on flexible Parylene-C substrates
Authors:
  Ali Khiat, Simone Cortese, Alexander Serb and Themistoklis Prodromakis. Nanotechnology 28, 025303, 2016.

Pt/TiO x/Pt resistive switching (RS) devices are considered to be amongst the most promising candidates in memristor family and the technology transfer to flexible substrates could open the way to new opportunities for flexible memory implementations.

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On the Origin of Resistive Switching Volatility in Ni/TiO2/Ni stacks
Authors:
  S. Cortese, M. Trapatseli, A. Khiat and T. Prodromakis. Journal of Applied Physics, 120, 065104, 2016.

Resistive switching and resistive random access memories have attracted huge interest for next generation nonvolatile memory applications, also thought to be able to overcome flash memories limitations when arranged in crossbar arrays.

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Unsupervised learning in probabilistic neural networks with multi-state metal-oxide memristive synapses
Authors:
  A. Serb, J. Bill, A. Khiat, R. Berdan, R. Legenstein and T. Prodromakis. Nature Communications 7, 12611, 2016.

In an increasingly data-rich world the need for developing computing systems that cannot only process, but ideally also interpret big data is becoming continuously more pressing.

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Real-time encoding and compression of neuronal spikes by metal-oxide memristor
Authors:
  I. Gupta, A. Serb, A. Khiat, R. Zeitler, S. Vassanelli, and T. Prodromakis. Nature Communications 7, 12805, 2016.

Advanced brain-chip interfaces with numerous recording sites bear great potential for investigation of neuroprosthetic applications. The bottleneck towards achieving an efficient bio-electronic link is the real-time processing of neuronal signals, which imposes excessive requirements on bandwidth, energy and computation capacity.

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Engineering the switching dynamics of TiO2 RRAM with Al doping
Authors:
  M. Trapatseli, A. Khiat, S. Cortese, A. Serb, D. Carta and T. Prodromakis. Journal of Applied Physics, 120, 025108, 2016.

Titanium oxide (TiOx) has attracted a lot of attention as an active material for resistive random access memory (RRAM), due to its versatility and variety of possible crystal phases.

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Investigation of the switching mechanism in TiO2-based RRAM: a two-dimensional EDX approach
Authors:
  D.Carta, I. Salaoru, A. Regoutz, A. Khiat, C. Mitterbauer, N.M. Harrison and T. Prodromakis. ACS Applied Materials and Interfaces, 10.1021/acsami.6b04919, 2016

The next generation of nonvolatile memory storage may well be based on resistive switching in metal oxides. TiO2 as transition metal oxide has been widely used as active layer for the fabrication of a variety of multistate memory nanostructure devices.

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High Density Crossbar Arrays with Sub- 15 nm Single Cells via Liftoff Process Only
Authors:
  A.Khiat, P. Ayliffe and T. Prodromakis. Scientific Reports, 6, 32614, 2016.

Emerging nano-scale technologies are pushing the fabrication boundaries at their limits, for leveraging an even higher density of nano-devices towards reaching 4F2/cell footprint in 3D arrays.

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X-ray Spectromicroscopy Investigation of Soft and Hard Breakdown in RRAM Devices
Authors:
  J34. D. Carta, P. Guttmann, A. Regoutz, A. Khiat, A. Serb, I. Gupta and T. Prodromakis. Nanotechnology, vol. 27, no. 34, 345705, 2016.

Resistive random access memory (RRAM) is considered an attractive candidate for next generation memory devices due to its competitive scalability, low-power operation and high switching speed.

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An FPGA-based instrument for en-masse RRAM characterisation with ns pulsing resolution
Authors:
  J. Xing, A. Serb, A. Khiat, R. Berdan, X. Hui and T. Prodromakis. IEEE Trans. CAS-I, vol. 63, no. 6, 2016.

An FPGA-based instrument with capabilities of on-board oscilloscope and nanoscale pulsing (70 ns @ ±10 V) is presented, thus allowing exploration of the nano-scale switching of RRAM devices.

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Spatially resolved TiOx phases in RRAM conductive nanofilaments using soft X-ray spectromicroscopy
Authors:
  D. Carta, A. Hitchcock, P. Guttmann, A. Regoutz, A. Khiat, A. Serb, I. Gupta, and T. Prodromakis. Scientific Reports, 6, 21525, 2016

Reduction in metal-oxide thin films has been suggested as the key mechanism responsible for forming conductive nanofilaments within solid-state memory devices, enabling their resistive switching capacity.

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Emulating short-term synaptic dynamics with memristive devices
Authors:
  R.Berdan, E. Vasilaki, A. Khiat, G. Indiveri, A. Serb, and T. Prodromakis. Scientific Reports, 6, 18639, 2016.

Neuromorphic architectures offer great promise for achieving computation capacities beyond conventional Von Neumann machines. The essential elements for achieving this vision are highly scalable synaptic mimics that do not undermine biological fidelity.

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Role and optimization of the active oxide layer in TiO2-based RRAM
Authors:
  A. Regoutz, I. Gupta, A. Serb, A. Khiat, F. Borgatti, T.-L. Lee, C. Schlueter, P. Torelli, B. Gobaut, M. Light, D. Carta, S. Pearce, G. Panaccione, and T. Prodromakis. Advanced Functional Materials, 26, 507–513, 2016.

TiO2 is commonly used as the active switching layer in resistive random access memory. The electrical characteristics of these devices are directly related to the fundamental conditions inside the TiO2 layer and at the interfaces between it and the surrounding electrodes.

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Analog Hfox-Rram Switches for Neural Networks
Authors:
  S34. S. Spiga, S. Brivo, E. Covi, M. Fanciulli, A. Serb, T. Prodromakis, H. Mostafa and G. Indiveri. Proceedings of the Electrochemical Society, Oct 2016.

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EU COST Action IC1401 – Pushing the Frontiers of Memristive Devices to Systems
Authors:
  D. Biolek, S. Cararra, E. Chicca, F. Corinto, J. Georgiou, B. Linares-Barranco, T. Prodromakis, S. Spiga and R. Tetzlaff. Published by: MELECON Mediterranean Electrotechnical Conference, April 2016

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HfO2-Based Memristors for Neuromorphic Applications
Authors:
  E. Covi, S. Brivo, A. Serb, T. Prodromakis, M. Fanciulli and S. Spiga. Published by: Proceedings of the IEEE International Symposium on Circuits and Systems, May 2016.

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An Ultra-Low Voltage RRAM Read-Out Technique Employing Dithering Principles
Authors:
  J. Xing, A. Serb and T. Prodromakis. Published by: Proceedings of the IEEE International Symposium on Circuits and Systems, May 2016

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Live Demonstration: Characterization of RRAM Crossbar Arrays at a Click of a Button
Authors:
  R. Berdan, A. Serb, A. Khiat, C. Papavassiliou and T. Prodromakis. Published by: Proceedings of the IEEE International Symposium on Circuits and Systems, May 2016

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Volatile Resistive Switching in Ni/TiO2/Ni stacks for Access Devices Applications
Authors:
  S. Cortese, A. Khiat and T. Prodromakis. Publiehsed by: UK Semiconductor, July 2016.

Resistive switching and resistive random access memories have attracted huge interest for next generation nonvolatile memory applications, also thought to be able to overcome flash memories limitations when arranged in crossbar arrays.

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Towards a memristor-based spike-sorting platform
Authors:
  I. Gupta, A. Serb, A. Khiat and T. Prodromakis, Published by: Proceedings of the IEEE Biomedical Circuits and Systems (BioCAS) Conference, Oct 2016.

We present a new approach for performing spikesorting through a memristor-based, neural-signal processing platform.

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Practical Operation Consideration for Memristive Integrating Sensors
Authors:
  I.Gupta, A.Serb, A. Khiat, T. Prodromakis. International Symposium on Circuits and Systems, 2016

In this work, we study the effect of different sets of operational parameters (pre-amplification i.e gain and offset, sampling rate) on the response of a typical TiOx MIS device to a reference pre-processed neural recording.

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A TiO2-based Volatile Threshold Switching Selector Device with 10^7 non linearity and sub 100 pA Off Current
Authors:
  Simone Cortese, Maria Trapatseli, Ali Khiat and Themistoklis Prodromakis, Proceedings of VLSI-TSA, Taiwan, April 2016

An highly non-linear two-terminal selector device is proposed: the device is 5 nm thick TiO2-based selector which exploits a volatile threshold resistive switching, so far unreported for this material. The device shows a current density up to 100 kA/cm2, 10^7 current non-linearity and a 4 V voltage margin, the highest reported for TiO2-based selectors and sub 100 pA off current.

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An amorphous titanium dioxide metal insulator metal selector device for resistive random access memory crossbar arrays with tunable voltage margin
Authors:
  Simone Cortese, Ali Khiat, Daniela Carta, Mark E. Light and Themis Prodromakis, Applied Physics Letters, 108, 033505 (2016); http://dx.doi.org/10.1063/1.4940361

In this study we present a selector device based on a nickel/sub-stoichiometric amorphous titanium dioxide film with an high Voltage Margin of 3 V in order to effectively tackle ReRAM crossbar arrays sneak currents. Its unique feature lies in the possibility of tuning of the voltage margin by simple device annealing steps,up to 40, which resulted in a improved Voltage Margin of 1.4 V without compromising the device behaviour in terms of Current and non linearity.

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An RRAM biasing parameter optimiser
Authors:
  A. Serb, A. Khiat, and T. Prodromakis. IEEE Trans. on Electron Devices, vol. 62, no.11, 2015.

Research on memory devices is a highly active field, and many new technologies are being constantly developed. However, characterizing them and understanding how to bias for optimal performance are becoming an increasingly tight bottleneck.

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Practical determination of individual element resistive states in selectorless RRAM arrays
Authors:
  A. Serb, W.R. White, C. Papavassiliou and T. Prodromakis. IEEE Trans. CAS-I, vol. 62, no. 11, 2015

Three distinct methods of reading multi-level cross-point resistive states from selector-less RRAM arrays are implemented in a physical system and compared for read-out accuracy.

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Implementation of a spike-based perceptron learning rule using TiO2−x memristors
Authors:
  H. Mostafa, A. Khiat, A. Serb, C. Mayr, G. Indiveri, T. Prodromakis. Frontiers in Neuroscience, vol. 9, no. 357, 2015.

Synaptic plasticity plays a crucial role in allowing neural networks to learn and adapt to various input environments. Neuromorphic systems need to implement plastic synapses to obtain basic “cognitive” capabilities such as learning.

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A μ-controller-based system for interfacing selector-less RRAM crossbar arrays
Authors:
  R. Berdan, A. Serb, A. Khiat, A. Regoutz, C. Papavassiliou, and T. Prodromakis. IEEE Transactions on Electron Devices, vol. 62, no. 7, 2015.

Selectorless crossbar arrays of resistive randomaccess memory (RRAM), also known as memristors, conduct large sneak currents during operation, which can significantly corrupt the accuracy of cross-point analog resistance (Mt) measurements.

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Gradual set dynamics in HfO2-based memristor driven by sub-threshold voltage pulses
Authors:
  S. Brivio, E. Covi, A. Serb, T. Prodromakis, M. Fanciulli, and S. Spiga. MEMRISYS 2015.

The switching dynamics of filamentary Pt/HfO 2/TiN memristive devices is managed through sub-threshold pulses in order to display gradual resistance decrease useful for analog logic computation based on spiking networks.

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Easily integrable Metal-Insulator-Metal (MIM) Selector Devices for High Density ReRAM Crossbar Arrays
Authors:
  S. Cortese, A. Khiat, T. Prodromakis. International Workshop on Advances in ReRAM: Materials & Interfaces, Oct 2015.

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A cell classifier for RRAM process development
Authors:
  Isha Gupta, Alexantrou Serb, Radu Berdan, Ali Khiat, Anna Regoutz, and Themis Prodromakis. IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—II: EXPRESS BRIEFS, VOL. 62, NO. 7, JULY 2015

In this brief, we develop and experimentally test an algorithm for identifying promising devices within an “array under study.”The objective is to identify devices that switch between highly distinct resistive states, i.e., a low resistive state (LRS) and a high resistive state (HRS) when subjected to a given biasing protocol.

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X-ray Absorption Spectroscopy Study of TiO2-x Thin Films for Memory Applications
Authors:
  D. Carta, G. Mountjoy, A. Regoutz, A. Khiat, A. Serb, T. Prodromakis. Published by American Chemical Society, Journal of Physical Chemistry C, 119, 8, 4362, (2015)

X-ray absorption spectroscopy (XAS) at the Ti K-edge was used to characterize the atomic-scale structure of a TiO2-x thin film before and after annealing and for the first time after inclusion in a metal-insulator-metal device based on a Cr/Pt/TiO2-x/Pt stack.

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Conductive Atomic Force Microscopy Investigation of Switching Thresholds in Titanium Dioxide Thin Films
Authors:
  Maria Trapatseli, Daniela Carta, Anna Regoutz, Ali Khiat, Alexander Serb, Isha Gupta, and Themistoklis Prodromakis, Journal of Physical Chemistry C, 119, 21, 11958, (2015).

In this work, we have used conductive atomic force microscopy (C-AFM) to identify the resistive switching thresholds of titanium dioxide thin films deposited on Si/SiO2/Ti/Pt stacks to be used in memory devices.

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Coexistence of Memory-Resistance and Memory-Capacitance in TiO2 Solid State Devices
Authors:
  Iulia Salaoru, Qingjiang Li, Ali Khiat and Themistoklis Prodromakis. Published by: Nanoscale Research Letters, September 2014.

This work exploits the coexistence of both resistance and capacitance memory effects in TiO2 based two terminal cells.

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Stochastic switching of TiO2-based memristive with identical initial memory states
Authors:
  Qingjiang Li, Ali Khiat, Iulia Salaoru, Hui Xu and Themistoklis Prodromakis. Published by: Nanoscale Research Letters 2014, 9:293

In this work, we show that identical TiO2-based memristive devices that possess the same initial resistive states are only phenomenologically similar as their internal structures may vary significantly, which could render quite dissimilar switching dynamics.

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Memory Impedance in TiO2 based Metal-Insulator-Metal Devices
Authors:
  Qingjiang Li, Ali Khiat, Iulia Salaoru, Christos Papavassiliou, and Themistoklis Prodromakis. Published by: Scientific Reports 2014

Here we demonstrate that TiO2-based metal-insulator-metal devices are more than just a memory-resistor. They possess resistive, capacitive and inductive components that can concurrently be programmed; essentially exhibiting a convolution of memristive, memcapacitive and meminductive effects.

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A versatile, low-cost platform for testing large ReRAM cross-bar arrays
Authors:
  Serb, A., Berdan, R., Khiat, A., Papavassiliou, C. and Prodromakis, T. Published by: IEEE ISCAS-CAS-FEST 1-5 June 2014, Melbourne, Australia

We demonstrate a testing platform that allows the manipulation of memristor cross-bar arrays by use of little more than a computer with MATLAB, an mBED and some external components mounted on a PCB.

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Origin of stochastic resistive switching in devices with phenomenologically identical initial states
Authors:
  Qingjiang, Li, Khiat, A., Salaoru, I., Hui, X. and Prodromakis, T. Published by: IEEE ISCAS-CAS-FEST 1-5 June 2014, Melbourne, Australia

Nanoscale resistive switching devices are nowadays widely employed in applications of storage, logic and computing.

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Qualitative SPICE modeling accounting for volatile dynamics of TiO2 memristors
Authors:
  Berdan, R., Khiat, A., Papavassiliou, C. and Prodromakis, T. Published by: IEEE ISCAS-CAS-FEST 1-5 June 2014, Melbourne, Australia

We propose a SPICE model that describes qualitatively real memristor device operation.

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Memristors as synapse emulators in the context of event-based computation
Authors:
  Serb, A., Berdan, R., Khiat, A., Shari, L., Vasilaki, E., Papavassiliou, C. and Prodromakis, T. Published by: IEEE ISCAS-CAS-FEST 1-5 June 2014, Melbourne, Australia

This paper examines the widespread Biolek and Pershin models of the memristor in order to find out whether they support STDP in an event-based computation environment.

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Applications of solid-state memristors in tunable filters
Authors:
  Wizenberg, R., Khiat, A., Berdan, R., Papavassiliou, C. and Prodromakis, T. Published by: IEEE ISCAS-CAS-FEST 1-5 June 2014, Melbourne, Australia

In this paper we present a practical approach to employ solid-state TiO2 memristors as tunable loads in filter configurations.

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Origin of the OFF state variability in ReRAM cells
Authors:
  Salaoru, I., Khiat, A., Berdan, R., Quingjian, L., Papavassiliou, C. and Prodromakis, T. Published by: Journal of Physics D: Applied Physics, 47, 145102, 2014

This work exploits the switching dynamics of nanoscale Resistive Random Access Memory (ReRAM) cells with particular emphasis on the origin of the observed variability when consecutively cycled/programmed at distinct memory states.

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Resistive switching characteristics of indium-tin-oxide thin film devices
Authors:
  Ali Khiat, Iulia Salaoru, and Themistoklis Prodromakis. Published by: Phys. Status Solidi A, 1–6 (2014) / DOI 10.1002/pssa.201330646

We demonstrate that indium–tin-oxide (ITO), when used as an active core material in metal–insulator–metal type devices, facilitates resistive switching. We fabricated devices both on silicon as well as quartz wafers, to demonstrate transparent devices.

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A Memristor SPICE Model Accounting for Volatile Characteristics of Practical ReRAM
Authors:
  Radu Berdan, Chuan Lim, Ali Khiat, Christos Papavassiliou. Published by: IEEE ELECTRON DEVICE LETTERS, VOL. 35, NO. 1, JANUARY 2014

Realizing large-scale circuits utilizing emerging nanoionic devices known as memristors depends on the accurate modeling of their behavior under a wide range of biasing conditions.

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Integration of nanoscale memristor synapses in neuromorphic computing architectures
Authors:
  G. Indiveri, B. Linares-Barranco, R. Legenstein, G. Deligeorgis and T. Prodromakis. Nanotechnology, 24, 384010, 2013

Conventional neuro-computing architectures and artificial neural networks have often been developed with no or loose connections to neuroscience.

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A Proposal for Hybrid Memristor-CMOS Spiking Neuromorphic Learning Systems
Authors:
  T Serrano-Gotarredona, T. Prodromakis, and B Linares-Barranco. IEEE Circuits and Systems Magazine, vol. 12, no. 2, pp. 74-88, May 2013.

Recent research in nanotechnology has led to the practical realization of nanoscale devices that behave as memristors, a device that was postulated in the seventies by Chua based on circuit theoretical reasonings.

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Resistive switching of oxygen enhanced TiO2 thin-film devices
Authors:
  I. Salaoru, T. Prodromakis, A. Khiat and C. Toumazou. Applied Physics Letters, vol. 102, 013506, 2013.

In this work, we investigate the effect of oxygen-enhanced TiO2 thin films on the switching dynamics of Pt/TiO2/Pt memristive nanodevices.

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STDP and STDP Variations with Memristors
Authors:
  T. Serrano-Gotarredona, T. Masquelier, T. Prodromakis, G. Indiveri, and B. Linares-Barranco. Published by: Frontiers in Neuroscience, vol. 7, no. 2, 2013.

In this paper we review several ways of realizing asynchronous Spike-Timing-Dependent-Plasticity (STDP) using memristors as synapses.

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Pulse-induced resistive and capacitive switching in TiO2 thin film devices
Authors:
  Iulia Salaoru, Ali Khiat, Qingjiang Li, Radu Berdan, and Themistoklis Prodromakis. Applied Physics Letters 103, 233513 (2013); doi: 10.1063/1.4840316

In this study, we exploit the non-zero crossing current–voltage characteristics exhibited by nanoscale TiO2 based solid-state memristors.

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Computing Motion with 3D Memristive Grid
Authors:
  C.K.K. Lim and T. Prodromakis. arXiv:1303.3067, Mar 2013

Computing the relative motion of objects is an important navigation task that we routinely perform by relying on inherently unreliable biological cells in the retina.

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Computing shortest paths in 2D and 3D memristive network
Authors:
  Z. Ye, M. Wu-Shihong and T. Prodromakis. Mar 2013

Global optimisation problems in networks often require shortest path length computations to determine the most efficient route.

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Integration of nanoscale memristor synapses in neuromorphic computing architectures
Authors:
  G. Indiveri, B. Linares-Barranco, R. Legenstein, G. Deligeorgis and T. Prodromakis. arXiv:1302.7007, Feb 2013

Conventional neuro-computing architectures and artificial neural networks have often been developed with no or loose connections to neuroscience.

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Memristive Devices as Parameter Setting Elements in Programmable Gain Amplifiers
Authors:
  R. Berdan, T. Prodromakis, I. Salaoru, A. Khiat and C. Toumazou. Applied Physics Letters, vol. 101, 243502, 2012.

In this paper, we investigate the AC performance of a variable gain amplifier that utilizes an in-house manufactured memristor as a gain setting element.

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High Precision Analogue Memristor Tuning
Authors:
  R. Berdan, T. Prodromakis and C. Toumazou. IET Electronic Letters 48, Issue: 18, August 30, 2012.

A report is presented on the operation of an analogue programming circuit for accurately setting the state of a memristor.

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Two Centuries of Memristors
Authors:
  T. Prodromakis, C. Toumazou and L.O. Chua. Nature Materials, vol. 11, no 6, pp. 478-481, Jun 2012.

Memristors are dynamic electronic devices whose nanoscale realization has led to considerable research interest. However, their experimental history goes back two centuries.

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Biomimetic Model of the Outer Plexiform Layer by Incorporating Memristive Devices
Authors:
  A. Gelencser, T. Prodromakis, C. Toumazou and T. Roska. Phys. Rev. E., vol. 85, Apr 2012.

In this paper we present a biorealistic model for the first part of the early vision of processing by incorporating memristive nanodevices.

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Modelling of Current Percolation Channels in Emerging Resistive Switching Elements
Authors:
  M. Wu-Shihong, T. Prodromakis, I. Salaoru and C. Toumazou. arXiv:1206.2746, June 2012

Metallic oxides encased within Metal-Insulator-Metal (MIM) structures can demonstrate both unipolar and bipolar switching mechanisms, rendering them the capability to exhibit a multitude of resistive states and ultimately function as memory elements.

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Memristors: Two centuries on
Authors:
  Themistoklis Prodromakis, Christofer Toumazou, and Leon Chua. Nature Conference: Frontiers in Electronic Materials, Aachen, 2012

Nanoscale implementations of memory-resistors are currently showcased as prospective solutions to emerging memory and unconventional computing.

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Concurrent resistive and capacitive state switching of nanoscale RiO2 memristors
Authors:
  Themistoklis Prodromakis, Iulia Salaoru, Ali Khiat, Christopher Toumazou. Nature Conference: Frontiers in Electronic Materials, Aachen, 2012

Memristive phenomena1 has taken an important place in research on physical switching mechanisms.

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A Versatile Memristor Model With Non-linear Dopant Kinetics
Authors:
  T. Prodromakis, B.P. Peh, C. Papavassiliou and C. Toumazou. IEEE Transactions on Electron Devices, vol. 58, no. 9, 2011.

The need for reliable models that take into account the nonlinear kinetics of dopants is nowadays of paramount importance, particularly with the physical dimensions of electron devices shrinking to the deep nanoscale range and the development of emerging nanoionic systems such as the memristor.

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A Biomimetic Model of the Outer Plexiform Layer by Incorporating Memristive Devices
Authors:
  Andras Gelencser, Themistoklis Prodromakis, Christofer Toumazou, Tamas Roska. arXiv:1112.0655, Dec 2011

In this paper we present a biorealistic model for the first part of the early vision processing by incorporating memristive nanodevices.

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Cost-effective fabrication of nanoscale electrode memristors with reproducible electrical response
Authors:
  K. Michelakis, T. Prodromakis and C. Toumazou. IET Micro and Nano Letters, vol. 5, no. 2, pp. 91-94, 2010.

This Letter aims to promote basic research into memristors, which will help provide theorists with much-needed reliable benchmarks and will also aid the technology progress.

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Switching mechanisms in microscale Memristors
Authors:
  T. Prodromakis, K. Michelakis and C. Toumazou. IET Electronic Letters, vol. 46, no. 1, pp. 63-65, 2010.

It is only very recently that the memristor, the fourth missing passive element, was discovered, as technological advances and the scaling-down to nanometre dimensions in particular resulted in clearly evident and measurable memristance.