Temperature dependent evolution of local structure in chalcogenide-based superlattices

Lotnyk, Andriy; Hilmi, Isom; Behrens, Mario; Rauschenbach, B.

doi:10.1016/j.apsusc.2020.147959

Cited by 45 publications

(26 citation statements)

References 62 publications

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“…a-c) Atomic-resolution HAADF-STEM images of the superlattices grown at the deposition temperatures of 100, 185, and 220 C. a-c) Reproduced with permission. [89] Copyright 2021, Elsevier. d,e) The evolution of resistance as a function of programming current and the evolution of current as a function of programming voltage.…”

Section: Artificial Synapses and Neuronsmentioning

confidence: 99%

“…[ 88 ] Lotnyk et al researched the evolution of the local structure in GeTe/Sb 2 Te 3 superlattice at different growing substrate temperatures, as shown in Figure . [ 89 ] They found that the Ge–Sb–Te alloy was formed in all the growing temperature ranges from 100 to 220 °C. For the low growing temperature, the intermixing results from the chemically induced phenomena, and the alloy represents a single unit which contains 19Te planes, as shown in Figure 4a.…”

Section: Materials and Mechanismmentioning

confidence: 99%

mentioning

confidence: 99%

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Exploring Phase‐Change Memory: From Material Systems to Device Physics

Ren

Sun

Chen³

et al. 2021

Physica Rapid Research Ltrs

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To deal with the growing demand for data storage and processing, phase‐change memory (PCM) provides one of the most promising candidates for next‐generation nonvolatile data storage and neuromorphic computing applications. A lot of effort has been made toward optimizing the materials and device design; thus, excellent device performances have been achieved including high density, fast switching speed, great endurance, and retention. In addition, the widely tunable optical characteristics of PCMs are irresistibly attractive for optoelectronic or all‐optical applications with unprecedented bandwidth, low energy consumption, and multilevel data storage. Herein, the materials system and switching mechanisms on experimental and modeling methods for PCM designs and applications are discussed. Electric‐domain and optical‐domain PCM‐based artificial synapses/neurons and their applications in neuromorphic computing are also reviewed. Finally, the future prospects and challenges of PCM‐based applications on materials, devices, algorithms, and system levels are highlighted.

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Section: Artificial Synapses and Neuronsmentioning

confidence: 99%

Section: Materials and Mechanismmentioning

confidence: 99%

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Exploring Phase‐Change Memory: From Material Systems to Device Physics

Ren

Sun

Chen³

et al. 2021

Physica Rapid Research Ltrs

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“…Similar results are obtained by growing the superlattices by pulsed laser deposition. [ 16 ] These blocks also occur in the stable bulk phase of the corresponding GST stoichiometry. In summary, it is shown that intercalating GeTe into Sb 2 Te 3 quintuple layers (QLs) is thermodynamically preferred, ruling out switching models that rely on a separation of these two compounds and on Ge atoms lying close to vdW gaps.…”

Section: Figurementioning

confidence: 99%

Absence of Partial Amorphization in GeSbTe Chalcogenide Superlattices

Evang

Mazzarello

2020

Physica Rapid Research Ltrs

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Phase‐change materials (PCMs) are widely used for optical data storage due to their fast and reversible transitions between a crystalline and an amorphous phase that exhibit reflectivity contrast. In the last decade, PCMs have been found to be promising candidates for the development of nonvolatile electronic memories, as well. In this context, superlattices of thin layers of GeTe and Sb2Te3 show an unprecedented performance gain in terms of switching speed and power consumption with respect to bulk GeSbTe compounds. Models of crystalline–crystalline transitions, proposed to explain the improved properties, however, are challenged by recent experiments in which GeTe–Sb2Te3 superlattices are observed to reconfigure toward a van der Waals heterostructure of rhombohedral GeSbTe and Sb2Te3. Herein, ab initio molecular dynamics simulations are used to explore an alternative switching mechanism that comprises amorphous–crystalline transitions of ultrathin GeSbTe layers between crystalline Sb2Te3. Despite some positive results obtained by tailoring the quenching protocol, overall the extensive simulations do not yield clear evidence for this mechanism. Therefore, they suggest that the switching process probably involves a transition between two crystalline states.

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“…[19][20][21] However, a few studies showed that superlattice-like structures of GeTe-Sb 2 Te 3 exhibit the tendency to intermix during deposition. [22][23][24][25][26] Searching for new compositions with other elements should be a promising way to further optimize the superlattice-based PCM. The crystallization temperature of Sb 2 Te 3 is too low to be utilized in practical products.…”

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confidence: 99%

Electrical and Mechanical Properties Enhancement in Superlattice‐Like GaSb/Ge₂Sb₂Te₅ Phase Change Thin Films

Yin

Wang

et al. 2021

Adv Materials Inter

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lower thermal conductivity of superlattice thin films compared to that of bulk materials. [8][9][10] In recent years, superlattice structure PCM has drawn the most attention in the field since they reduce the energy consumption while can still maintain other good performances (such as density, speed, endurance, and signal contrast) and realize controllable multilevel storage to increase storage density. [11][12][13] From the viewpoint of thermodynamics, the smaller the cell size, the less the input energy can be, thus superlattice structure phase change materials were theoretically designed based on suppressing the ratio of a mixing entropy from the beginning and reducing the energy consumption. [14] The explanation for these improvements is still under debate, their atomic structure and switching mechanism need to be explored. [15] Materials with two or three metastable intermediate resistance levels are promising candidates for multi-level data storage devices. [16][17][18] A multilayer PCM thin film generally comprises two PCM constituents alternatively deposited, with one phase of high phase change speed and the other phase of good amorphous stability. Most PCM materials are compounds located in pseudo-binary line GeTe-Sb 2 Te 3 showing high distinguishable phases and cyclability, scalability. [19][20][21] However, a few studies showed that superlattice-like structures of GeTe-Sb 2 Te 3 exhibit the tendency to intermix during deposition. [22][23][24][25][26] Searching for new compositions with other elements should be a promising way to further optimize the superlattice-based PCM. The crystallization temperature of Sb 2 Te 3 is too low to be utilized in practical products. [27] Ge 2 Sb 2 Te 5 is the core composition in almost all PCMs owing to comprehensive properties, it was reported by Yamada et al. [28,29] GaSb layer has also been proposed for phase change materials since their unique crystallization process is effective in enhancing thermal stability. [30][31][32] Especially, Ga-Sb thin films exhibited an unusual behavior with a decreasing mass density upon crystallization compared to GeTe thin films, [33] which can compensate for an increased density of GST thin films. The recent studies [9,34] evidenced that the superlattice PCM provides an effective means to tune and balance the properties such as thermal stability and read/write speed of the device. On the other hand, the mechanical properties of superlattice thin films have been proved to show abnormal effects with super-hardness and super-modulus in certain ranges.

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Temperature dependent evolution of local structure in chalcogenide-based superlattices

Cited by 45 publications

References 62 publications

Exploring Phase‐Change Memory: From Material Systems to Device Physics

Exploring Phase‐Change Memory: From Material Systems to Device Physics

Absence of Partial Amorphization in GeSbTe Chalcogenide Superlattices

Electrical and Mechanical Properties Enhancement in Superlattice‐Like GaSb/Ge₂Sb₂Te₅ Phase Change Thin Films

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Temperature dependent evolution of local structure in chalcogenide-based superlattices

Cited by 45 publications

References 62 publications

Exploring Phase‐Change Memory: From Material Systems to Device Physics

Exploring Phase‐Change Memory: From Material Systems to Device Physics

Absence of Partial Amorphization in GeSbTe Chalcogenide Superlattices

Electrical and Mechanical Properties Enhancement in Superlattice‐Like GaSb/Ge2Sb2Te5 Phase Change Thin Films

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Electrical and Mechanical Properties Enhancement in Superlattice‐Like GaSb/Ge₂Sb₂Te₅ Phase Change Thin Films