Thermoelectric heating of Ge2Sb2Te5 in phase change memory devices

Suh, Dongseok; Kim, Cheolkyu; Kim, Kijoon H. P.; Kang, Youn-Seon; Lee, Tae-Yon; Khang, Yoonho; Park, Tae Sang; Yoon, Young-Gui; Im, Jino; Ihm, Jisoon

doi:10.1063/1.3259649

Cited by 39 publications

(19 citation statements)

References 13 publications

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“…The position of the amorphous region changes with the bias polarity in PCM cells because Thomson heating alters the temperature distribution during the reset operation. The bias-polarity-dependent behavior was also shown by Suh et al in vertical PCM cells while testing different electrode materials [2]. Their cell performance varies for the electrode material with different Seebeck coefficient due to another thermoelectric effect, known as the Peltier effect.…”

Section: Introductionmentioning

confidence: 53%

“…in which C is the volumetric heat capacity, T is temperature, t is time, k is the thermal conductivity, ρ is the electrical resistivity, j is current density, and µ T is the Thomson coefficient. The equations (2) and 3are coupled with the Laplace equation (∇(σ ∇φ) = 0, where σ is the electrical conductivity and φ is electrical potential). Equation equation 3captures Thomson heating within a homogeneous material.…”

Section: Simulation Detailsmentioning

confidence: 99%

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Impact of thermoelectric phenomena on phase-change memory performance metrics and scaling

2012

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The coupled transport of heat and electrical current, or thermoelectric phenomena, can strongly influence the temperature distribution and figures of merit for phase-change memory (PCM). This paper simulates PCM devices with careful attention to thermoelectric transport and the resulting impact on programming current during the reset operation. The electrothermal simulations consider Thomson heating within the phase-change material and Peltier heating at the electrode interface. Using representative values for the Thomson and Seebeck coefficients extracted from our past measurements of these properties, we predict a cell temperature increase of 44% and a decrease in the programming current of 16%. Scaling arguments indicate that the impact of thermoelectric phenomena becomes greater with smaller dimensions due to enhanced thermal confinement. This work estimates the scaling of this reduction in programming current as electrode contact areas are reduced down to 10 nm × 10 nm. Precise understanding of thermoelectric phenomena and their impact on device performance is a critical part of PCM design strategies.

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Section: Introductionmentioning

confidence: 53%

Section: Simulation Detailsmentioning

confidence: 99%

Impact of thermoelectric phenomena on phase-change memory performance metrics and scaling

2012

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“…28 Moreover, GST can be used as a thermoelectric heater and thermal barrier to improve the memory performance. 29,30 However, low-voltage programming adversely affects the retention characteristics of chalcogenide-based CBRAM devices, giving rise to the voltage-time dilemma. 1,31 It is hence critical to control the formation and rupture of the filamentary conductive channels to improve the resistive switching characteristics of CBRAM devices.…”

Section: Introductionmentioning

confidence: 99%

Forming-free, bi-directional polarity conductive-bridge memory devices with Ge2Sb2Te5 solid-state electrolyte and Ag active electrode

Huang

Chen

et al. 2015

Journal of Applied Physics

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Preparation and characteristics of conductive-bridge random access memory devices containing Ge2Sb2Te5 (GST) chalcogenide as the solid-state electrolyte, Ag as the active electrode, and W-Ti as the counter electrode are presented. As revealed by the electrical measurement, only the samples containing crystalline GST exhibited the resistive switching behaviors. With an insertion of ZnS-SiO2 dielectric layer at the Ag/GST interface and a postannealing at 100 °C for 1 min, the sample exhibited the best electrical performance with satisfactory cycleability and retention properties. Moreover, the forming-free and bi-directional polarity features were observed in such a sample type. Microstructure and composition analyses found the finely dispersed nano-scale Ag clusters in GST and, when electrical bias is applied, the migrating Ag ions may build up the connections in between neighboring Ag clusters. Moreover, grain boundaries in polycrystalline GST might be the main paths for Ag migration. The thread-like conduction channels in GST hence form, leading to the low resistance state of sample. On the contrary, the depletion of Ag in GST broke the connections in between Ag clusters when the electrical bias is reversed. This led to the rupture of conduction channels and, hence, the high resistance state of sample. The low operational voltage, forming-free, and bi-directional polarity features observed in (AZGW)T sample might also originated from the fine dispersion of Ag clusters in GST electrolyte.

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“…Thermoelectric transport can have a large impact on the performance of semiconductor devices and related nanostructures. [1][2][3][4][5][6] The impact is possibly most pronounced in phase-change memories, which experience both large current densities and temperature excursions exceeding 600 C. Recent measurements provided evidence of thermoelectric transport in phase-change cells by capturing a modification in the amorphous region 1 and the programming condition 2 with the bias polarity. However, there are relatively few data for the thermoelectric properties of phase-change materials at the film thicknesses relevant for contemporary devices.…”

Section: Introductionmentioning

confidence: 99%

Phase purity and the thermoelectric properties of Ge2Sb2Te5 films down to 25 nm thickness

Lee

Kodama

Won

et al. 2012

Journal of Applied Physics

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Light-induced off-diagonal thermoelectric effect via indirect optical heating of incline-oriented CaxCoO2 thin film Appl. Phys. Lett. 100, 181907 (2012) Thermal artifact on the spin Seebeck effect in metallic thin films deposited on MgO substrates J. Appl. Phys. 111, 07B106 (2012) Evolution of structural and thermoelectric properties of indium-ion-implanted epitaxial GaAs Appl. Phys. Lett. 100, 102101 (2012) Interplay of point defects, biaxial strain, and thermal conductivity in homoepitaxial SrTiO3 thin films Thermoelectric phenomena strongly influence the behavior of chalcogenide materials in nanoelectronic devices including phase-change memory cells. This work uses a novel silicon-oninsulator experimental structure to measure the phase and temperature-dependent Seebeck and Thomson coefficients of Ge 2 Sb 2 Te 5 films including the first data for films of thickness down to 25 nm. The Ge 2 Sb 2 Te 5 films annealed at different temperatures contain varying fractions of the amorphous and crystalline phases which strongly influence the thermoelectric properties. The Seebeck coefficient reduces from 371 lV/K to 206 lV/K as the crystalline fraction increases by a factor of four as quantified using x-ray diffraction. The data are consistent with modeling based on effective medium theory and suggest that careful consideration of phase purity is needed to account for thermoelectric transport in phase change memory. V C 2012 American Institute of Physics.

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Thermoelectric heating of Ge2Sb2Te5 in phase change memory devices

Cited by 39 publications

References 13 publications

Impact of thermoelectric phenomena on phase-change memory performance metrics and scaling

Impact of thermoelectric phenomena on phase-change memory performance metrics and scaling

Forming-free, bi-directional polarity conductive-bridge memory devices with Ge2Sb2Te5 solid-state electrolyte and Ag active electrode

Phase purity and the thermoelectric properties of Ge2Sb2Te5 films down to 25 nm thickness

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