Disorder enhancement due to structural relaxation in amorphous Ge2Sb2Te5

Fantini, Paolo; Ferro, M.; Calderoni, A.; Brazzelli, S.

doi:10.1063/1.4720182

Cited by 28 publications

(15 citation statements)

References 26 publications

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“…Ref. 22. A succession of the two exponential regimes, i.e., Poolelike dependency at low voltages and Poole-Frenkel dependency at higher voltages, has also been observed.…”

Section: B Low-intermediate Field Behavior-model and Modeling Resultsmentioning

confidence: 89%

“…12,25 Instead of measuring r with optical methods, one could also attempt to extract it directly from the field-dependence of the conductivity in the PF-type region as, e.g., in Ref. 22. For a strict PF-type conductivity rðF; TÞ ¼ r 0 ðTÞ Á expðb ffiffiffi F p =k B TÞ, the logarithmic slope,…”

Section: B Low-intermediate Field Behavior-model and Modeling Resultsmentioning

confidence: 99%

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High-field electrical transport in amorphous phase-change materials

Kaes

Gallo

Sebastian

et al. 2015

Journal of Applied Physics

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Electrical transport in chalcogenide-based phase change materials is an active area of research owing to the prominent role played by these materials in the field of information technology. Here, we present transport measurements (IV curves) obtained on line-cells of as-deposited amorphous phase change materials (Ge2Sb2Te5, GeTe, Ag4In3Sb66Te27) over a wide voltage and temperature range (300 K to 160 K). The well defined geometry of our devices enables a description of the transport behavior in terms of conductivity vs. electric field. At higher temperatures (300 K ≥ T ≥ 220 K) and low to intermediate fields (F < 20 V/μm), the data can be described within the framework of a previously developed model, which is based on multiple trapping transport together with 3D Poole-Frenkel emission from a two-center Coulomb potential. Based on this model, we observe a temperature dependence of the inter-trap distance, which we can relate to a temperature dependence in the occupation of the defect creating the Coulomb potential governing Poole-Frenkel emission. At higher fields and lower temperatures, the dependency of the IV curve on the electric field can be described by ln(I/I0) = (F/Fc)2. By combining this contribution with that of the Poole-Frenkel emission, we can show that the slope at high fields, Fc, is independent of temperature. We argue that models based on direct tunneling or thermally assisted tunneling from a single defect into the valence band cannot explain the observed behavior quantitatively.

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“…Ref. 22. A succession of the two exponential regimes, i.e., Poolelike dependency at low voltages and Poole-Frenkel dependency at higher voltages, has also been observed.…”

Section: B Low-intermediate Field Behavior-model and Modeling Resultsmentioning

confidence: 89%

Section: B Low-intermediate Field Behavior-model and Modeling Resultsmentioning

confidence: 99%

High-field electrical transport in amorphous phase-change materials

Kaes

Gallo

Sebastian

et al. 2015

Journal of Applied Physics

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“…Qualitatively this scenario can be understood, since resonant bonding can only prevail for a moderate Peierls distortion. Hence, large local distortions become favourable in the amorphous state, where resonant bonding is absent 17,52 . As compared with other glassy systems, aging in GeTe displays peculiar features that set this system apart from the Zachariasen picture.…”

Section: Discussionmentioning

confidence: 99%

Aging mechanisms in amorphous phase-change materials

et al. 2015

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Aging is a ubiquitous phenomenon in glasses. In the case of phase-change materials, it leads to a drift in the electrical resistance, which hinders the development of ultrahigh density storage devices. Here we elucidate the aging process in amorphous GeTe, a prototypical phase-change material, by advanced numerical simulations, photothermal deflection spectroscopy and impedance spectroscopy experiments. We show that aging is accompanied by a progressive change of the local chemical order towards the crystalline one. Yet, the glass evolves towards a covalent amorphous network with increasing Peierls distortion, whose structural and electronic properties drift away from those of the resonantly bonded crystal. This behaviour sets phase-change materials apart from conventional glass-forming systems, which display the same local structure and bonding in both phases.

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“…However, such route suffers from the resistance drift issue of the amorphous part, which stems from the intrinsic aging property of the materials [99,100,101,102,103,104]. In addition, when the size of phase change memory devices is scaled down to few nanometers [105,106], such volume ratio strategy is no longer feasible to support many intermediate resistance states.…”

Section: Discussionmentioning

confidence: 99%

A Review on Disorder-Driven Metal–Insulator Transition in Crystalline Vacancy-Rich GeSbTe Phase-Change Materials

Wang

Mazzarello

et al. 2017

Materials

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Metal–insulator transition (MIT) is one of the most essential topics in condensed matter physics and materials science. The accompanied drastic change in electrical resistance can be exploited in electronic devices, such as data storage and memory technology. It is generally accepted that the underlying mechanism of most MITs is an interplay of electron correlation effects (Mott type) and disorder effects (Anderson type), and to disentangle the two effects is difficult. Recent progress on the crystalline Ge1Sb2Te4 (GST) compound provides compelling evidence for a disorder-driven MIT. In this work, we discuss the presence of strong disorder in GST, and elucidate its effects on electron localization and transport properties. We also show how the degree of disorder in GST can be reduced via thermal annealing, triggering a disorder-driven metal–insulator transition. The resistance switching by disorder tuning in crystalline GST may enable novel multilevel data storage devices.

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Disorder enhancement due to structural relaxation in amorphous Ge2Sb2Te5

Cited by 28 publications

References 26 publications

High-field electrical transport in amorphous phase-change materials

High-field electrical transport in amorphous phase-change materials

Aging mechanisms in amorphous phase-change materials

A Review on Disorder-Driven Metal–Insulator Transition in Crystalline Vacancy-Rich GeSbTe Phase-Change Materials

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