A model structure for interfacial phase change memories: Epitaxial trigonal Ge1Sb2Te4

Hardtdegen, H.; Rieß, Sally; Schuck, Martin; Keller, K.; Jost, Peter; Du, Hongchu; Bornhöfft, Manuel; Schwedt, Alexander; Mußler, Gregor; Ahe, Martina von der; Mayer, Joachim; Roth, Georg; Grützmacher, Detlev; Mikulics, M.

doi:10.1016/j.jallcom.2016.04.013

Cited by 46 publications

(28 citation statements)

References 32 publications

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“…After the discovery of the attractive properties of graphene, useful in several different applicationss uch as electronics, [1] catalysis, [2] electrochemistry, [3] energy storagea nd conversion, [4,5] mechanical hardener, [6] corrosion protection, [7] etc., other 2D materials have attracted much attentiond ue to other extraordinary properties [8,9] rising especially when reducing the thickness of the material to single layer,a nd which can complementw ith those of graphene. [10][11][12][13] For example semiconductingm aterials with ad irect band gap could be more appropriate for optoelectronic applications than the zero-band gap graphene.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Exfoliation of MoS₂ Crystal for Hydrogen Electrogeneration

Ambrosi

Pumera

2018

Chemistry A European J

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Transition metal dichalcogenides (TMDs) have recently emerged within the group of 2D materials due to their electrical, catalytic and optical properties significantly enhanced and useful when down-sized to single layer.I n particular,MoS 2 has attracted much attention due to its semiconducting nature with au seful band gap when presenta s single layer,t he enhanced photoluminescence, but also importantly the excellent catalytic properties towards the electrochemical hydrogen evolution. We present heret he preparation of thin layers MoS 2 nanosheetsw ith enhanced catalytic properties towards the hydrogen evolution reaction by meanso fa ne asy and fast electrochemical top-down exfoliation procedurei na queous solution from an aturally occurring MoS 2 crystal. After structurala nd chemical characterization with STEM, AFM, XPS and Raman spectroscopy electrochemicali nvestigationsw ere performed to test catalytic properties in acidic solution for the electrogeneration of hydrogen and compare it to MoS 2 nanosheets obtained through the widelye mployed chemical Li intercalation/exfoliation. Electrochemically exfoliated MoS 2 shows lower Ta fel slope than its counterparto btainedw ithc hemical exfoliation.[a] Dr.A .Ambrosi, Prof. Dr.M .P umera DivisionofChemistry &B iological Chemistry SchoolofP hysical and Mathematical SciencesSupporting information containing STEM images of chemically exfoliated MoS 2 and XPS survey spectra of chemically and electrochemically exfoliated MoS 2 ,and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

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Section: Introductionmentioning

confidence: 99%

Electrochemical Exfoliation of MoS₂ Crystal for Hydrogen Electrogeneration

Ambrosi

Pumera

2018

Chemistry A European J

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“…Consequently, stacking disorder appears to be typical for layered GST225 compounds22. It is worth mentioning that no chemical disorder was reported for the trigonal GST124 phase2023. The stacking disorder in the GST225 phase is attributed to deviations in local chemical composition of GST thin films.…”

Section: Resultsmentioning

confidence: 99%

Local atomic arrangements and lattice distortions in layered Ge-Sb-Te crystal structures

Lotnyk

Roß

Bernütz

et al. 2016

Sci Rep

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Insights into the local atomic arrangements of layered Ge-Sb-Te compounds are of particular importance from a fundamental point of view and for data storage applications. In this view, a detailed knowledge of the atomic structure in such alloys is central to understanding the functional properties both in the more commonly utilized amorphous–crystalline transition and in recently proposed interfacial phase change memory based on the transition between two crystalline structures. Aberration-corrected scanning transmission electron microscopy allows direct imaging of local arrangement in the crystalline lattice with atomic resolution. However, due to the non-trivial influence of thermal diffuse scattering on the high-angle scattering signal, a detailed examination of the image contrast requires comparison with theoretical image simulations. This work reveals the local atomic structure of trigonal Ge-Sb-Te thin films by using a combination of direct imaging of the atomic columns and theoretical image simulation approaches. The results show that the thin films are prone to the formation of stacking disorder with individual building blocks of the Ge2Sb2Te5, Ge1Sb2Te4 and Ge3Sb2Te6 crystal structures intercalated within randomly oriented grains. The comparison with image simulations based on various theoretical models reveals intermixed cation layers with pronounced local lattice distortions, exceeding those reported in literature.

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“…The periodicity of the structure is 21 atomic layers along the z direction. Regarding the xy plane, it is evidenced by both X-ray diffraction and transmission electron microscopy experiments that chemical disorder could be present in the cation-like layers [66,67], see STEM-HAADF images in Figure 3b,c. If there is no chemical disorder, two cationic-like layers should have the same brightness as the Te layers, as the atomic number of Sb (51) is very close to that of Te (52).…”

Section: Discussionmentioning

confidence: 99%

“…The brighter dots indicate Te atomic columns, whereas darker dots are Ge/Sb atomic columns. Adapted with permission from References [66,67] © 2015 The Royal Society of Chemistry; 2016 Elsevier Ltd.…”

Section: Figurementioning

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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A model structure for interfacial phase change memories: Epitaxial trigonal Ge1Sb2Te4

Cited by 46 publications

References 32 publications

Electrochemical Exfoliation of MoS₂ Crystal for Hydrogen Electrogeneration

Electrochemical Exfoliation of MoS₂ Crystal for Hydrogen Electrogeneration

Local atomic arrangements and lattice distortions in layered Ge-Sb-Te crystal structures

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

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A model structure for interfacial phase change memories: Epitaxial trigonal Ge1Sb2Te4

Cited by 46 publications

References 32 publications

Electrochemical Exfoliation of MoS2 Crystal for Hydrogen Electrogeneration

Electrochemical Exfoliation of MoS2 Crystal for Hydrogen Electrogeneration

Local atomic arrangements and lattice distortions in layered Ge-Sb-Te crystal structures

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

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Product

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Electrochemical Exfoliation of MoS₂ Crystal for Hydrogen Electrogeneration

Electrochemical Exfoliation of MoS₂ Crystal for Hydrogen Electrogeneration