Thermal conductivity anisotropy and grain structure in Ge2Sb2Te5 films

Lee, Jae-Ho; Li, Zijian; Reifenberg, John P.; Lee, Sangchul; Sinclair, Robert; Asheghi, Mehdi; Goodson, Kenneth E.

doi:10.1063/1.3573505

Cited by 78 publications

(66 citation statements)

References 32 publications

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“…history, geometry, neighboring materials, and process details [131,132]. Rapid temperature transients and gradients can produce phase impurities, which have a strong influence on thermal transport [126,127,133], as well as electrical [134], thermoelectric [135], and mechanical properties [136]. An additional (and fundamentally enticing) complexity is Downloaded by [New York University] at 07: 56 12 June 2015 the strongly differing roles of electron and phonon transport depending on the material phase, as shown by the thermal conductivity data in Figure 2c.…”

Section: Phase Change Memoriesmentioning

confidence: 99%

“…(b) Schematic illustration of the programming pulses, which require extreme temperature transients, which involve complex electrothermal phenomena. (c) Room-temperature thermal conductivity data for Ge 2 Sb 2 Te 5 films [114][115][116][117][118][119][120][121][122][123][124][125][126][127][128][129][130]. The circles are obtained from the 3ω measurements [114, 115, 119-121, 126, 127] and the diamonds are obtained from the TDTR measurements [116-118, 122-125, 128-130].…”

Section: Phase Change Memoriesmentioning

confidence: 99%

“…The PCM research community has leveraged and extended the TDTR and 3ω methodologies to reveal a variety of the fascinating thermal transport phenomena that occur in the phase-change chalcogenides [114][115][116][117][118][119][120][121][122][123][124][125][126][127][128][129][130]. The TDTR methodology has proven useful for extracting coupled (and even decoupling [125]) film and interface properties.…”

Section: Phase Change Memoriesmentioning

confidence: 99%

“…The TDTR methodology has proven useful for extracting coupled (and even decoupling [125]) film and interface properties. The 3ω measurement approach has been applied in the framework of novel experimental geometries to characterize the in-plane thermal conductivity [126] and the impact of rapid heating events [127]. Thermal transport studies of PCM materials are challenging due to complex impacts of the several material phases that can coexist depending on temperature Downloaded by [New York University] at 07:56 12 June 2015 Figure 2 (a) Cross-sectional transmission electron micrograph (TEM) of phase change memory devices, which store data bits through thermally induced phase transitions in Ge 2 Sb 2 Te 5 .…”

Section: Phase Change Memoriesmentioning

confidence: 99%

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Evaluating Broader Impacts of Nanoscale Thermal Transport Research

Shi

Dames

Lukes

et al. 2015

Nanoscale and Microscale Thermophysical Engineering

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The past two decades have witnessed the emergence and rapid growth of the research field of nanoscale thermal transport. Much of the work in this field has been fundamental studies that have explored the mechanisms of heat transport in nanoscale films, wires, particles, interfaces, and channels. However, in recent years there has been an increasing emphasis on utilizing the fundamental knowledge gained toward understanding and improving Manuscript 128 L. SHI ET AL.device and system performances. In this opinion article, an attempt is made to provide an evaluation of the existing and potential impacts of the basic research efforts in this field on the developments of the heat transfer discipline, workforce, and a number of technologies, including heat-assisted magnetic recording, phase change memories, thermal management of microelectronics, thermoelectric energy conversion, thermal energy storage, building and vehicle heating and cooling, manufacturing, and biomedical devices. The goal is to identify successful examples, significant challenges, and potential opportunities where thermal science research in nanoscale has been or will be a game changer.

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Section: Phase Change Memoriesmentioning

confidence: 99%

Section: Phase Change Memoriesmentioning

confidence: 99%

Section: Phase Change Memoriesmentioning

confidence: 99%

Section: Phase Change Memoriesmentioning

confidence: 99%

See 2 more Smart Citations

Evaluating Broader Impacts of Nanoscale Thermal Transport Research

Shi

Dames

Lukes

et al. 2015

Nanoscale and Microscale Thermophysical Engineering

Self Cite

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“…The Seebeck coefficients for the Ge 2 Sb 2 Te 5 (GST) films of various thicknesses and for the phase purity such as amorphous and crystalline phases have been reported. 10,11 There are two types of crystal structure in the GST compounds. One is the metastable rocksalt structure with Te atoms occupying sites on one face-centered-cubic (FCC) sublattice, and Ge and Sb randomly forming the other FCC sublattice.…”

mentioning

confidence: 99%

Effect of Structural Change on Thermoelectric Properties of the Chalcogenide Ge₂Sb₂Te₅Thin Films

Hong

Yoon

2014

ECS J. Solid State Sci. Technol.

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Ge 2 Sb 2 Te 5 (GST) films grown onto SiO 2 (250 nm)/Si substrate at room temperature were annealed at various temperatures to investigate the structural variations. The GST films changed from amorphous to face-centered cubic (FCC) and hexagonal closed packed (HCP) crystalline phases as the annealing temperature increases and the samples annealed at 380 • C showed co-existence of the FCC and the HCP. Samples annealed at 380 • C showed the highest charge carrier concentration, the lowest resistivity, and the highest power factor. © The Author ( Highly efficient thin thermoelectric films have recently gained acceptance for potential applications in the microelectronics industry as sensors, microcoolers, and as low-power generators.1,2 Thermoelectric transport can have a large impact on the performance of semiconductor devices and related nanostructures.3-5 Compared with the conventional mechanical devices, thermoelectric devices have the advantages such as maintenance-free, better transient response. 6,7 The primary candidate technology for miniaturizing thermoelectric devices is to apply semiconductor-processing technologies including thin film fabrication. The efficiency of conversion is described by the dimensionless, thermoelectric figure-of-merit, ZT = S 2 T/ρκ, where S is the Seebeck coefficient, T is the absolute temperature, ρ is the electrical resistivity, and κ is the total thermal conductivity. A high ZT may be achieved by reducing κ and by enhancing the thermoelectric power factor, P = S 2 /ρ. The interrelated Seebeck coefficient, electrical conductivity, and thermal conductivity make it difficult to improve one transport property without affecting the others. 8 The key issue of micro-thermoelectric devices is how to fabricate thin films with high performance by semiconductor-processing technologies.Various chalcogenide materials reported that the holes are responsible for their positive Seebeck coefficient. 9 The Seebeck coefficient is strongly depended on the phase and the processing conditions. The Seebeck coefficients for the Ge 2 Sb 2 Te 5 (GST) films of various thicknesses and for the phase purity such as amorphous and crystalline phases have been reported. 10,11 There are two types of crystal structure in the GST compounds. One is the metastable rocksalt structure with Te atoms occupying sites on one face-centered-cubic (FCC) sublattice, and Ge and Sb randomly forming the other FCC sublattice. The other is the hexagonal structure (HCP), which is composed of Te layers forming a complicated cubic close packed structure with Ge and Sb atoms randomly occupying the octahedral interstices. Friedrich et al. reported that the temperature dependent measurements of the electrical resistance have been employed to study structural changes in direct current (dc) sputtered GST films.12 Using the films with a thickness between 80 and 250 nm, they reported that the pronounced changes of film resistance due to structural changes enabled a precise determination of transition temperature and activation energies. T...

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