Structural and optical properties of optimized amorphous GeTe films for memory applications

Gâlcă, A.C.; Sava, F.; Şimăndan, Iosif‐Daniel; Bucur, Cristina; Dumitru, V.; Poroşnicu, C.; Mihai, Claudia; Velea, A.

doi:10.1016/j.jnoncrysol.2018.07.007

Cited by 26 publications

(10 citation statements)

References 49 publications

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“…The appearance of novel doublets with 4d 5/2 peaks at 43.6, 43.1 and 42.6 eV is ascribed to the formation of TeO 2 (10% of the total spectral area), TeO (15.5% of the total spectral area), and TeO x species (12.5% of the total spectral area). [ 28–30 ] Similar conclusions are obtained from analysis of the Te‐3d core level (Figure S6b, Supporting Information).…”

Section: Resultssupporting

confidence: 78%

Transition‐Metal Dichalcogenide NiTe₂: An Ambient‐Stable Material for Catalysis and Nanoelectronics

Nappini

Boukhvalov

D’Olimpio

et al. 2020

Adv Funct Materials

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By means of theory and experiments, the application capability of nickel ditelluride (NiTe 2 ) transition-metal dichalcogenide in catalysis and nanoelectronics is assessed. The Te surface termination forms a TeO 2 skin in an oxygen environment. In ambient atmosphere, passivation is achieved in less than 30 min with the TeO 2 skin having a thickness of about 7 Å. NiTe 2 shows outstanding tolerance to CO exposure and stability in water environment, with subsequent good performance in both hydrogen and oxygen evolution reactions. NiTe 2 -based devices consistently demonstrate superb ambient stability over a timescale as long as one month. Specifically, NiTe 2 has been implemented in a device that exhibits both superior performance and environmental stability at frequencies above 40 GHz, with possible applications as a receiver beyond the cutoff frequency of a nanotransistor.

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Section: Resultssupporting

confidence: 78%

Transition‐Metal Dichalcogenide NiTe₂: An Ambient‐Stable Material for Catalysis and Nanoelectronics

Nappini

Boukhvalov

D’Olimpio

et al. 2020

Adv Funct Materials

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“…The MS sample is not completely crystalline: it has 18% amorphous phase left. It was shown that the films obtained by magnetron sputtering crystallize at a higher temperature than in the case of PLD [10,30]. On the other hand, in the other two samples (PLD and MSPLD), a minor hexagonal GeSb 4 Te 4 is obtained, which can be regarded as a seed for the hcp-GST-225 formation at a higher annealing temperature [3].…”

Section: X-ray Diffractionmentioning

confidence: 95%

“…Phase change materials are known to exhibit deposition-dependent optical and structural properties, such as mass density, optical bandgap and refractive index [10]. GST-225 films have been successfully obtained through a wide variety of deposition techniques such as magnetron sputtering [11], pulsed laser deposition [12], atomic layer deposition [13], chemical vapor deposition [14], etc.…”

Section: Introductionmentioning

confidence: 99%

Influence of Deposition Method on the Structural and Optical Properties of Ge2Sb2Te5

et al. 2021

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Ge2Sb2Te5 (GST-225) is a chalcogenide material with applications in nonvolatile memories. However, chalcogenide material properties are dependent on the deposition technique. GST-225 thin films were prepared using three deposition methods: magnetron sputtering (MS), pulsed laser deposition (PLD) and a deposition technique that combines MS and PLD, namely MSPLD. In the MSPLD technique, the same bulk target is used for sputtering but also for PLD at the same time. The structural and optical properties of the as-deposited and annealed thin films were characterized by Rutherford backscattering spectrometry, X-ray reflectometry, X-ray diffraction, Raman spectroscopy and spectroscopic ellipsometry. MS has the advantage of easily leading to fully amorphous films and to a single crystalline phase after annealing. MS also produces the highest optical contrast between the as-deposited and annealed films. PLD leads to the best stoichiometric transfer, whereas the annealed MSPLD films have the highest mass density. All the as-deposited films obtained with the three methods have a similar optical bandgap of approximately 0.7 eV, which decreases after annealing, mostly in the case of the MS sample. This study reveals that the properties of GST-225 are significantly influenced by the deposition technique, and the proper method should be selected when targeting a specific application. In particular, for electrical and optical phase change memories, MS is the best suited deposition method.

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“…The real part of the dielectric function, ε 1 , is related to ε 2 by the Kramers–Kronig relation. The optical dielectric constant, ε ∞ , is the low energy-limit of ε 1 and can be computed as ε ∞ = ε 1 (0.05 eV) 66 . The electronic transitions are described by the resonance energy E 0 of bound electrons oscillations, the broadening parameter Γ representing the scattering time of the carriers and the amplitude A given by the number of carriers making these transitions.…”

Section: Methodsmentioning

confidence: 99%

Structural and optical properties of amorphous Si–Ge–Te thin films prepared by combinatorial sputtering

Mihai

Sava

Şimăndan

et al. 2021

Sci Rep

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The lack of order in amorphous chalcogenides offers them novel properties but also adds increased challenges in the discovery and design of advanced functional materials. The amorphous compositions in the Si–Ge–Te system are of interest for many applications such as optical data storage, optical sensors and Ovonic threshold switches. But an extended exploration of this system is still missing. In this study, magnetron co-sputtering is used for the combinatorial synthesis of thin film libraries, outside the glass formation domain. Compositional, structural and optical properties are investigated and discussed in the framework of topological constraint theory. The materials in the library are classified as stressed-rigid amorphous networks. The bandgap is heavily influenced by the Te content while the near-IR refractive index dependence on Ge concentration shows a minimum, which could be exploited in applications. A transition from a disordered to a more ordered amorphous network at 60 at% Te, is observed. The thermal stability study shows that the formed crystalline phases are dictated by the concentration of Ge and Te. New amorphous compositions in the Si–Ge–Te system were found and their properties explored, thus enabling an informed and rapid material selection and design for applications.

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Structural and optical properties of optimized amorphous GeTe films for memory applications

Cited by 26 publications

References 49 publications

Transition‐Metal Dichalcogenide NiTe₂: An Ambient‐Stable Material for Catalysis and Nanoelectronics

Transition‐Metal Dichalcogenide NiTe₂: An Ambient‐Stable Material for Catalysis and Nanoelectronics

Influence of Deposition Method on the Structural and Optical Properties of Ge2Sb2Te5

Structural and optical properties of amorphous Si–Ge–Te thin films prepared by combinatorial sputtering

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Structural and optical properties of optimized amorphous GeTe films for memory applications

Cited by 26 publications

References 49 publications

Transition‐Metal Dichalcogenide NiTe2: An Ambient‐Stable Material for Catalysis and Nanoelectronics

Transition‐Metal Dichalcogenide NiTe2: An Ambient‐Stable Material for Catalysis and Nanoelectronics

Influence of Deposition Method on the Structural and Optical Properties of Ge2Sb2Te5

Structural and optical properties of amorphous Si–Ge–Te thin films prepared by combinatorial sputtering

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Transition‐Metal Dichalcogenide NiTe₂: An Ambient‐Stable Material for Catalysis and Nanoelectronics

Transition‐Metal Dichalcogenide NiTe₂: An Ambient‐Stable Material for Catalysis and Nanoelectronics