On the Mechanisms of Ni‐Catalysed Graphene Chemical Vapour Deposition

Weatherup, Robert S.; Bayer, Bernhard C.; Blume, Raoul; Baehtz, Carsten; Kidambi, Piran R.; Fouquet, Martin; Wirth, Christoph; Schlögl, Robert; Hofmann, Stephan

doi:10.1002/cphc.201101020

Cited by 96 publications

(173 citation statements)

References 26 publications

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“…In the presence of nickel oxide (NiO), hydroxide (Ni(OH) 2 ) and oxyhydroxide (γ-NiOOH), clear XPS lines should appear at 854.7 eV, 855.3 eV and 855.8 eV respectively [23,24,25], and the energy difference between the Ni 2p 3/2 peak and the bulk plasmon satellite should be reduced to 5.8 eV, in the presence of NiO, and to 5.3 eV, in the presence of Ni(OH) 2 . On the other hand, in case of carbon contamination of the Ni substrate during CVD growth, a peak corresponding to the Ni-C binding energy should appear at 853 eV [26]. Our XPS spectra reveal none of these [see Fig.…”

mentioning

confidence: 77%

Voltage-controlled inversion of tunnel magnetoresistance in epitaxial nickel/graphene/MgO/cobalt junctions

Godel

Kamalakar

Doudin

et al. 2014

Applied Physics Letters

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Spin-based memory and logic devices are the subject of an intense research activity motivated by the perspective to overcome power, performance and architectural bottlenecks of CMOS-based devices. Among potential material candidates in this field, graphene (Gr) carries great expectations because of its unique electronic transport properties. So far, graphene has been employed mainly in "lateral" spintronic devices, where ferromagnetic electrodes are deposited on top of graphene and electron current flows in the plane of the carbon sheet [1,2,3]. In such devices, oxide tunnel barriers (MgO or Al 2 O 3 ) are often inserted between graphene and the ferromagnetic metals to overcome the conductance mismatch problem [4,5], allowing spin-polarized electrons to be efficiently injected into or extracted

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mentioning

confidence: 77%

Voltage-controlled inversion of tunnel magnetoresistance in epitaxial nickel/graphene/MgO/cobalt junctions

Godel

Kamalakar

Doudin

et al. 2014

Applied Physics Letters

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“…We attribute this self-terminating growth to the grown layers blocking the precursor supply to the Ni catalyst. 5 The spin probe analyzer electrode geometry was defined in a second ebeam step. A 1 µm x 1 µm window was opened in UVIII resist on top of the GPFE.…”

Section: Methodsmentioning

confidence: 99%

Graphene-Passivated Nickel as an Oxidation-Resistant Electrode for Spintronics

et al. 2012

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We report on graphene-passivated ferromagnetic electrodes (GPFE) for spin devices. GPFE are shown to act as spin-polarized oxidation-resistant electrodes. The direct coating of nickel with few layer graphene through a readily scalable chemical vapour deposition (CVD) process allows the preservation of an unoxidized nickel surface upon air exposure. Fabrication and measurement of complete reference tunneling spin valve structures demonstrates that the GPFE is maintained as a spin polarizer and also that the presence of the graphene coating leads to a specific sign reversal of the magnetoresistance. Hence, this work highlights a novel oxidation-resistant spin source which further unlocks low cost wet chemistry processes for spintronics devices.Information storage is today mainly based on magnetism, with hundreds of millions of hard drives sold every year, 1,2 and further growth is expected driven by the proliferation of enormous data centers for online "cloud" computing. Spintronics is at the heart of this nonvolatile data-storage revolution, with ferromagnetic memory elements acting as basic building blocks: spin sources or analyzers. The efficiency of spin polarized electrodes, based on ferromagnetic metals like nickel and cobalt, thereby heavily relies on the quality of the interfaces at play. A major challenge for device processing and integration is to prevent detrimental corrosion and oxidation of the ferromagnetic metals in use. To date, this severely

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“…The parameter space of these processes has only recently been investigated by in situ x-ray photoelectron spectroscopy (XPS) measurements during CVD growth, allowing careful understanding of the mechanisms at play [18,49]. Usually, growth is enabled at temperatures >600 °C, but a fine tuning of the processes allowed the growth to be limited to a monolayer and the temperature to be lowered down to 450 °C and below (thus compatible with the usual CMOS processing) [18,50]. This highlights the effort required to achieve high-quality FM/ graphene interfaces.…”

Section: Direct Integration Of Graphene In Mtj By Cvdmentioning

confidence: 99%