Graphene overcoats for ultra-high storage density magnetic media

Dwivedi, Neeraj; Ott, Anna K.; Sasikumar, Kiran; Dou, Chunmeng; Yeo, Reuben J.; Narayanan, Badri; Sassi, Ugo; Fazio, Domenico De; Soavi, Giancarlo; Dutta, Tanmay; Balcı, Osman; Shinde, Sachin M.; Zhang, J.; Katiyar, Ajay; Keatley, P. S.; Srivastava, Avanish Kumar; Sankaranarayanan, Subramanian K. R. S.; Ferrari, Andrea C.; Bhatia, Charanjit S.

doi:10.1038/s41467-021-22687-y

Cited by 21 publications

(14 citation statements)

References 85 publications

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“…The SLG crystals are characterized throughout the fabrication process by Raman spectroscopy with a Renishaw InVia at 532 nm, laser power ∼1 mW, and acquisition time ∼4s. The laser spot size is ∼0.8 μm, as determined by the razor blade technique. , We present a detailed step-by-step procedure to acquire and analyze Raman spectra throughout the fabrication of wafer scale SLG-based devices. This ensures quality control as well as reproducibility.…”

Section: Results and Discussionmentioning

confidence: 99%

Wafer-Scale Integration of Graphene-Based Photonic Devices

et al. 2021

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Graphene and related materials can lead to disruptive advances in next-generation photonics and optoelectronics. The challenge is to devise growth, transfer and fabrication protocols providing high (≥5000 cm 2 V –1 s –1 ) mobility devices with reliable performance at the wafer scale. Here, we present a flow for the integration of graphene in photonics circuits. This relies on chemical vapor deposition (CVD) of single layer graphene (SLG) matrices comprising up to ∼12000 individual single crystals, grown to match the geometrical configuration of the devices in the photonic circuit. This is followed by a transfer approach which guarantees coverage over ∼80% of the device area, and integrity for up to 150 mm wafers, with room temperature mobility ∼5000 cm 2 V –1 s –1 . We use this process flow to demonstrate double SLG electro-absorption modulators with modulation efficiency ∼0.25, 0.45, 0.75, 1 dB V –1 for device lengths ∼30, 60, 90, 120 μm. The data rate is up to 20 Gbps. Encapsulation with single-layer hexagonal boron nitride (hBN) is used to protect SLG during plasma-enhanced CVD of Si 3 N 4 , ensuring reproducible device performance. The processes are compatible with full automation. This paves the way for large scale production of graphene-based photonic devices.

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Section: Results and Discussionmentioning

confidence: 99%

Wafer-Scale Integration of Graphene-Based Photonic Devices

et al. 2021

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“…In this subsection, we derive the «fast» term of the kinetic temperature 𝑇 𝐹 (𝑥), corresponding to equilibration of the kinetic and potential energies. Using the assumption (10) with 𝑎∆𝑁 ≪ 𝒜 and ∆𝑁 ≫ 1, we introduce continuous functions 𝑇 𝐹 (𝑥), 𝑔 𝐹 𝑐 (𝑥, 𝑦) such that…”

Section: Fast Termmentioning

confidence: 99%

Unsteady thermal transport in an instantly heated semi-infinite free end Hooke chain

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2022

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We deal with unsteady ballistic heat transport in a semi-infinite Hooke chain with free end caused by instantaneous heat pulse. An analytical description of the evolution of the kinetic temperature is proposed in both discrete and continuum formulations in the frameworks of the lattice dynamics approach. We show analytically a property of thermal wave to reflect from the free end. Continuum description of the transient processes, caused by this reflection, has restrictions. In particular, the kinetic temperature field near the boundary and also evolution of the kinetic temperature at the boundary are inadequately described via the continuum model. Based on the comparison of descriptions of heat propagation in the semi-infinite and infinite Hooke chains, we formulate the principles of symmetry of the discrete and continuum solutions.

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“…Apart from these concerns, 1−4 layer graphene that had been transferred on hard disk media has shown excellent tribological, corrosion, and thermal stability characteristics. 19 Nonetheless, to date, no subnanometer overcoat is available that can efficiently address tribological concerns when it is deposited directly on diverse surfaces. Furthermore, at the tribological interfaces, the interaction of the sub-nanometer layer would greatly vary with surface topography, for example, the roughness and texture of the target surfaces, 20−22 the reason for which is not fully understood so far.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Recently, two-dimensional (2D) materials with thicknesses of one to a few atoms, such as graphene, have shown the potential for combating friction and wear concerns of several systems. ,, However, the requirements of high temperature for processing and substrate-specific growth remain the concerns with graphene overcoats. Apart from these concerns, 1–4 layer graphene that had been transferred on hard disk media has shown excellent tribological, corrosion, and thermal stability characteristics . Nonetheless, to date, no sub-nanometer overcoat is available that can efficiently address tribological concerns when it is deposited directly on diverse surfaces.…”

Section: Introductionmentioning

confidence: 99%

Angstrom-Scale Transparent Overcoats: Interfacial Nitrogen-Driven Atomic Intermingling Promotes Lubricity and Surface Protection of Ultrathin Carbon

et al. 2021

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Lubricity, a phenomenon which enables the ease of motion of objects, and wear resistance, which minimizes material damage or degradation, are important fundamental characteristics for sustainable technology developments. Ultrathin coatings that promote lubricity and wear resistance are of huge importance for a number of applications, including magnetic storage and micro-/nanoelectromechanical systems. Conventional ultrathin coatings have, however, reached their limit. Graphene-based materials that have shown promise to reduce friction and wear have many intrinsic limitations such as high temperature and substrate-specific growth. To address these concerns, a great deal of research is currently ongoing to optimize graphene-based materials. Here we discover that angstrom-thick carbon (8 Å) significantly reduces interfacial friction and wear. This lubricant shows ultrahigh optical transparency and can be directly deposited on a wide range of surfaces at room temperature. Experiments combined with molecular dynamics simulations reveal that the lubricating efficacy of 8 Å carbon is further improved via interfacial nitrogen.

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Graphene overcoats for ultra-high storage density magnetic media

Cited by 21 publications

References 85 publications

Wafer-Scale Integration of Graphene-Based Photonic Devices

Wafer-Scale Integration of Graphene-Based Photonic Devices

Unsteady thermal transport in an instantly heated semi-infinite free end Hooke chain

Angstrom-Scale Transparent Overcoats: Interfacial Nitrogen-Driven Atomic Intermingling Promotes Lubricity and Surface Protection of Ultrathin Carbon

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