Li-intercalated graphene on SiC(0001): An STM study

Fiori, Sara; Murata, Yuya; Veronesi, S.; Rossi, Antonio; Heun, S.

doi:10.1103/physrevb.96.125429

Cited by 45 publications

(47 citation statements)

References 64 publications

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“…No appreciable D peak is retrieved and 2D peak position and full width at half maximum (FHWM) are entirely comparable to those of the asgrown material. 26 This confirms that the graphene quality is not affected by the processing. Raman and PL spectra of graphene and WS 2 as-grown and after processing steps are reported in ESI (Fig.…”

Section: Resultssupporting

confidence: 63%

Patterned tungsten disulfide/graphene heterostructures for efficient multifunctional optoelectronic devices

et al. 2018

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One of the major issues in graphene-based optoelectronics is to scale-up high-performing devices. In this work, we report an original approach for the fabrication of efficient optoelectronic devices from scalable tungsten disulfide (WS)/graphene heterostructures. Our approach allows for the patterned growth of WS on graphene and facilitates the realization of ohmic contacts. Photodetectors fabricated with WS on epitaxial graphene on silicon carbide (SiC) present, when illuminated with red light, a maximum responsivity R ∼220 A W, a detectivity D* ∼2.0 × 10 Jones and a -3 dB bandwidth of 250 Hz. The retrieved detectivity is 3 orders of magnitude higher than that obtained with graphene-only devices at the same wavelength. For shorter illumination wavelengths we observe a persistent photocurrent with a nearly complete charge retention, which originates from deep trap levels in the SiC substrate. This work ultimately demonstrates that WS/graphene optoelectronic devices with promising performances can be obtained in a scalable manner. Furthermore, by combining wavelength-selective memory, enhanced responsivity and fast detection, this system is of interest for the implementation of 2d-based data storage devices.

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Section: Resultssupporting

confidence: 63%

Patterned tungsten disulfide/graphene heterostructures for efficient multifunctional optoelectronic devices

et al. 2018

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“…Having about 1/3 of the volume, this supercell it is named S (small) as opposed to standard 13 × 13 (large, L), and it is about one order of magnitude less expensive in calculations. Furthermore, the pattern of buffer layer crests evaluated in S (Fiori et al, 2017) display a more regular hexagonal symmetry (see Figure 2B right side images and Figure 1C, central images), more similar in this respect to the high temperature determinations and to the hexagonal phases of occurring during the buffer formation. The DFT calculations of QFMLG bring further insights on the interplay between symmetry and substrate interaction.…”

Section: The Moiré Pattern: Unique or Not Unique?supporting

confidence: 57%

“…of the first one (becoming the monolayer graphene, MLG) or by intercalating hydrogen or metals (Fiori et al, 2017) underneath the buffer layer, leading to the formation of the so-called Quasi Free-standing MonoLayer Graphene (QFMLG) (Riedl et al, 2009) (see Figure 1A). The morphology of the three types of carbon layer is very different: The BL is strongly rippled (Bouhafs et al, 2017;, with peaked crests following a moiré pattern induced by the covalent interaction with the substrate (see Figures 1B,C); these in turn induce a (much less pronounced) corrugation in the overlying MLG, whose exact conformation (concave or convex), however, seems to depend on the environmental conditions influencing the weak BL-MLG van der Waals (vdW) interaction (Mallet et al, 2007;Telychko et al, 2015;Cavallucci and Tozzini, 2016).…”

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confidence: 99%

From the Buffer Layer to Graphene on Silicon Carbide: Exploring Morphologies by Computer Modeling

2019

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Epitaxial graphene grown by thermal Si decomposition of Silicon Carbide appears in different morphological variants, depending on the production conditions: the strongly rugged buffer layer, retaining a considerable amount of sp 3 hybridized buffer layer, the softly corrugated graphene monolayer and the rather flat quasi free standing monolayer with sparse small pits pinned to localized electronic states. Therefore, graphene on SiC is not a single material, but a set of materials with different morphologies depending on the environmental conditions during the synthesis. In all cases the distortion from the ideal flat structure seem to follow to some extent specific symmetries, which appear to preserve some memory of the interaction with the SiC bulk, even in the cases in which the sheet is substantially decoupled from it. Defects bear interesting properties, e.g., localized hot spots of reactivity and localized electronic states with specific energy depending on their nature and morphology, while their possible symmetric location is an added value for applications. Therefore, being capable of controlling the morphology, concentration, symmetry and location of the defects would allow tailoring this material for specific applications. Based on ab initio calculations and simulations, we first describe in detail the morphology of the different systems, and subsequently, we formulate hypotheses on the relationship between morphology and the formation process. We finally suggest future simulation studies capable of revealing the still unclear steps. These should give indication on how to tune the environmental conditions to control the final morphology of the sample and specifically design this material.

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“…This process transforms the buffer layer into quasi‐free standing graphene with recovered electronic properties . In addition to hydrogen, other intercalants have been explored including alkali metals (e.g., Li, Na, K, Cs,), Ca, Cu, Bi, Cr, Ge, and Si . Specifically, Li and Ca induce superconductivity in graphene, while Ge leads to interfacial ambipolar doping of graphene depending on local Ge coverage, allowing for the creation of 2D lateral p–n junctions .…”

Section: Control Of Surface and Interface Propertiesmentioning

confidence: 99%

Interface Characterization and Control of 2D Materials and Heterostructures

2018

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2D materials and heterostructures have attracted significant attention for a variety of nanoelectronic and optoelectronic applications. At the atomically thin limit, the material characteristics and functionalities are dominated by surface chemistry and interface coupling. Therefore, methods for comprehensively characterizing and precisely controlling surfaces and interfaces are required to realize the full technological potential of 2D materials. Here, the surface and interface properties that govern the performance of 2D materials are introduced. Then the experimental approaches that resolve surface and interface phenomena down to the atomic scale, as well as strategies that allow tuning and optimization of interfacial interactions in van der Waals heterostructures, are systematically reviewed. Finally, a future outlook that delineates the remaining challenges and opportunities for 2D material interface characterization and control is presented.

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Li-intercalated graphene on SiC(0001): An STM study

Cited by 45 publications

References 64 publications

Patterned tungsten disulfide/graphene heterostructures for efficient multifunctional optoelectronic devices

Patterned tungsten disulfide/graphene heterostructures for efficient multifunctional optoelectronic devices

From the Buffer Layer to Graphene on Silicon Carbide: Exploring Morphologies by Computer Modeling

Interface Characterization and Control of 2D Materials and Heterostructures

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