Threshold switching via electric field induced crystallization in phase-change memory devices

Diosdado, Jorge A. Vázquez; Ashwin, Peter; Koháry, K.; Wright, C. David

doi:10.1063/1.4729551

Cited by 27 publications

(13 citation statements)

References 28 publications

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“…In this manuscript we focus only on nucleation to establish at which field ranges and parameter values the electric field might play a significant role in "kickstarting" crystallization and therefore, as suggested in Refs. [7][8][9], be responsible for the characteristic threshold switching effect observed in [11] work that does include growth in the simulation of electric field induced crystallization produced broadly similar results presented in this paper.…”

Section: Kineticssupporting

confidence: 81%

“…[7][8][9]. Nevertheless, a more sophisticated analysis [11] requires carrying out physically realistic simulations of the threshold switching process in typical phase-change device structures, both with and without electric field dependent energy contributions to the system free energy in order to determine whether or not field induced nucleation is indeed the driving force behind characteristic threshold switching behavior in phase-change memories. The results presented in this manuscript show that the electric field has an influence on nucleation when it is of order 10 6 to 10 9 V/m.…”

Section: Discussionmentioning

confidence: 99%

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Role of Enthalpy and Relative Electric Permittivity in Electric Field Induced Nucleation

et al. 2012

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Emerging phase-change electrical memory technologies rely on the fast amorphous to crystalline transition, which is usually characterized by an 'S-shape' current-voltage curve. We investigate the possibility that electric field induced nucleation may play a dominant role in defining this characteristic electrical switching behavior. We derive quantitative crystallization maps to study the kinetics of the amorphous to crystalline transition in the presence of electric field contribution to the free energy and we investigate how the prediction of the electric field induced nucleation model is affected by material properties such as enthalpy and relative electric permittivity.

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Section: Kineticssupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Role of Enthalpy and Relative Electric Permittivity in Electric Field Induced Nucleation

et al. 2012

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“…2. Starting on the left hand side of the "U," the cell is in the amorphous high resistance ("reset") state and increasing the amplitude of the (pulsed) programming current reduces the cell resistance, due to the onset of crystallization (of course the programming voltage also needs to be above the threshold voltage for conduction in the amorphous state -see [12]). When the cell is fully crystallized the resistance reaches its minimum value ("set" state) at the bottom of the "U."…”

Section: Properties Of Multilevel Phase Change Memoriesmentioning

confidence: 99%

“…For such simulations of Fig. 1 a comprehensive physical model for the electrical, thermal and phase-transformation processes at work in the PCM cell was used (this physical model and its associated material parameters has been described extensively in previous publications (see [12], [14], and [15]), to which the reader is referred for further details). However, for this paper, as already discussed in §I, we are concerned with the development of a realistic PCM device model (in SPICE) that incorporates multilevel capabilities and the effects of resistance (and threshold voltage) drift.…”

Section: Properties Of Multilevel Phase Change Memoriesmentioning

confidence: 99%

A Model for Multilevel Phase-Change Memories Incorporating Resistance Drift Effects

Cobley

Wright

Diosdado

2015

IEEE J. Electron Devices Soc.

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Phase change memories are emerging as a most promising technology for future nonvolatile, solid-state, electrical storage. However, to compete effectively in mainstream storage applications, a multilevel cell capability is most desirable. Unfortunately, phase-change memories exhibit a temporal drift in programmed resistance (and in threshold switching voltage) which appears to be a fundamental and universal property of the amorphous or partially amorphous phase. Phase-change device models should therefore include these drift effects in a realistic way so that circuit and systems designers can assess the likely performance of multilevel phase-change memories in a variety of potential applications. In this paper, therefore, we present a comprehensive SPICE-based model for phase-change devices that includes the capability for programming into multiple resistance levels, the prediction of the drift of cell resistance (and threshold voltage) with time, and the capability for modeling the randomness inherent to the resistance drift phenomenon. Simulations of multilevel programming and drift phenomena using the model are presented and compared to experimental results, with which there is very good agreement.INDEX TERMS Nonvolatile memory, phase-change memory, memristors.

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“…This approach is potentially capable of spanning the length scales between ab initio atomistic modelling and bulk‐scale methods, such the JMAK formalism. Recently, this cellular automata approach has been combined with electro‐thermal simulations to carry out physically realistic simulations of the threshold switching process in typical phase‐change device structures, both with and without electric field dependent energy contributions to the system free energy 25, and to study arithmetic and memristor‐type devices based on phase‐change materials 26, 27.…”

Section: Nanoscale Phase‐transformationmentioning

confidence: 99%

Modelling the phase‐transition in phase‐change materials

Koháry

Wright

2013

Physica Status Solidi (b)

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Phase‐change materials have a wide range of optical and electrical applications due to a unique combination of structural, electronic and optical properties. The phase transition between the crystalline and amorphous phases is a central physical process in devices based on phase‐change materials. In order to design and to develop future applications with novel functionalities we need to understand on the nanometre length scale and the (sub)nanosecond timescale the electrical, thermal and phase‐transition behaviour of phase‐change materials. At the nanoscale the phase‐transformation in phase‐change materials is governed by the chemical composition, atomic structure, and the input energy due to temperature (Joule heat), electric field and/or electronic excitations. Therefore, a successful phase‐change model should capture all these elements and predict the phase information as an output. We discuss the theoretical models that have been used to study and predict the crystallization of phase‐change materials that span the materials modelling spectrum from electronic/atomistic simulations (atomic behaviour) to microscopic and continuum models (bulk behaviour). Real applications and device design require the use of microscopic and continuum models due to large computational times of atomistic simulations. On the other hand the predictions provided by microscopic and continuum models depend on the chosen parameter set used to describe the phase transition. We stress the importance of ‘building bridges’ between atomistic and continuum modelling to design future phase‐change devices with novel and enhanced functionalities.

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Threshold switching via electric field induced crystallization in phase-change memory devices

Cited by 27 publications

References 28 publications

Role of Enthalpy and Relative Electric Permittivity in Electric Field Induced Nucleation

Role of Enthalpy and Relative Electric Permittivity in Electric Field Induced Nucleation

A Model for Multilevel Phase-Change Memories Incorporating Resistance Drift Effects

Modelling the phase‐transition in phase‐change materials

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