Preferential carbon etching by hydrogen inside hexagonal voids of 6H-SiC(0001)

Sander, Dirk; Wulfhekel, Wulf; Hanbücken, M.; Nitsche, S.; Palmari, Jacqueline; Dulot, Frédéric; d’Avitaya, F. Arnaud; Leycuras, A.

doi:10.1063/1.1519962

Cited by 16 publications

(6 citation statements)

References 8 publications

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“…Moreover, the EGS observed here differ from exfoliated graphene bubbles reported previously [43] in a number of important ways; firstly, the identification of the exfoliated bubbles was done using optical microscopy with the use of Newton rings; however, due to the lower height of our EGS compared to the bubbles reported in [51,52], the Newton rings cannot be observed. Secondly, the characteristic dimensions of our EGS are smaller and orders of magnitude lower in height (≈1%) than those described in [52,32].…”

Section: Surface Morphology: Identification Of Epitaxial Graphene Nan...mentioning

confidence: 55%

“…These circles could not be attributed to the simple roughness of the surface, i.e. 0.5-2 nm, commonly observed for epitaxial graphene grown on 4H-SiC substrates [46,50,51], or defects due to their large size and location, far from terrace intersections. These features were further studied by supplementing AFM topography with simultaneous UFM nanomechanical mapping (figure 3), where the lateral resolution is maintained at approximately 2 nm.…”

Section: Surface Morphology: Identification Of Epitaxial Graphene Nan...mentioning

confidence: 90%

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Charged nano-domes and bubbles in epitaxial graphene

et al. 2014

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For the first time, new epitaxial graphene nano-structures resembling charged 'bubbles' and 'domes' are reported. A strong influence, arising from the change in morphology, on the graphene layer's electronic, mechanical and optical properties has been shown. The morphological properties of these structures have been studied with atomic force microscopy (AFM), ultrasonic force microscopy (UFM) and Raman spectroscopy. After initial optical microscopy observation of the graphene, a detailed description of the surface morphology, via AFM and nanomechanical UFM measurements, was obtained. Here, graphene nano-structures, domes and bubbles, ranging from a few tens of nanometres (150–200 nm) to a few μm in size have been identified. The AFM topographical and UFM stiffness data implied the freestanding nature of the graphene layer within the domes and bubbles, with heights on the order of 5–12 nm. Raman spectroscopy mappings of G and 2D bands and their ratio confirm not only the graphene composition of these structures but also the existence of step bunching, defect variations and the carrier density distribution. In particular, inside the bubbles and substrate there arises complex charge redistribution; in fact, the graphene bubble–substrate interface forms a charged capacitance. We have determined the strength of the electric field inside the bubble–substrate interface, which may lead to a minigap of the order of 5 meV opening for epitaxial graphene grown on 4H-SiC face-terminated carbon.

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Section: Surface Morphology: Identification Of Epitaxial Graphene Nan...mentioning

confidence: 55%

Section: Surface Morphology: Identification Of Epitaxial Graphene Nan...mentioning

confidence: 90%

Charged nano-domes and bubbles in epitaxial graphene

et al. 2014

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“…Well controlled sequent KOH etching (tracking etching) is suitable for detailed analysis of the nature and interactions of defects in SiC epitaxial layers [11,12]. High temperature etching in the vapour of KOH [13], in hydrogen [14] and in molten Si [5] enables also study of extended defects in SiC, but these techniques seem to be less convenient due to more demanding technical requirements.…”

Section: General Remarksmentioning

confidence: 99%

Defect‐selective etching of SiC

Weyher

Lazar

Borysiuk

et al. 2005

Physica Status Solidi (a)

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PACS 61.72.Ff, 82.50.Hp Two methods of defect-selective etching of SiC are described: (i) orthodox etching in molten KOH -NaOH eutectic with 10% of MgO powder (E + M etch) and (ii) electroless photo-etching in aqueous KOH solutions (PEC method). The first etch shows similar effectiveness in revealing different type of dislocations, micropipes and stacking faults, as the commonly used molten KOH. The second approach is new for studying defects in SiC and is most suitable for revealing stacking faults both on the disoriented (0001) basal planes and on the (1 100) cleavage surfaces. Cross-calibration of both techniques and examples of calibration of PEC etch features by TEM are shown.

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“…The observed electrical properties are significantly affected by doping and other parameters (e.g., stain, flake edges). Raman spectroscopy is a powerful technique to investigate graphene quality and doping [ 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 , 120 ]. Therefore, it is extremely informative to correlate Raman spectra with corresponding electrical behavior in graphene samples.…”

Section: Raman Investigation Of Electrical Properties In Epitaxialmentioning

confidence: 99%

“…Specifically, it was found that the Raman shift of the G band behaves symmetrically for equal electron and hole doping percentages around a doping minimum [ 115 ]. In addition, it was shown that the G band FWHM is reduced as the electron/hole doping is increased [ 117 , 118 ]. This occurs due to the Pauli exclusion principle that blocks the conversion of phonons into electron–hole pairs as soon as the electron–hole gap becomes larger than the phonon energy.…”

Section: Raman Investigation Of Electrical Properties In Epitaxialmentioning

confidence: 99%

Raman Spectroscopy Imaging of Exceptional Electronic Properties in Epitaxial Graphene Grown on SiC

et al. 2020

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Graphene distinctive electronic and optical properties have sparked intense interest throughout the scientific community bringing innovation and progress to many sectors of academia and industry. Graphene manufacturing has rapidly evolved since its discovery in 2004. The diverse growth methods of graphene have many comparative advantages in terms of size, shape, quality and cost. Specifically, epitaxial graphene is thermally grown on a silicon carbide (SiC) substrate. This type of graphene is unique due to its coexistence with the SiC underneath which makes the process of transferring graphene layers for devices manufacturing simple and robust. Raman analysis is a sensitive technique extensively used to explore nanocarbon material properties. Indeed, this method has been widely used in graphene studies in fundamental research and application fields. We review the principal Raman scattering processes in SiC substrate and demonstrate epitaxial graphene growth. We have identified the Raman bands signature of graphene for different layers number. The method could be readily adopted to characterize structural and exceptional electrical properties for various epitaxial graphene systems. Particularly, the variation of the charge carrier concentration in epitaxial graphene of different shapes and layers number have been precisely imaged. By comparing the intensity ratio of 2D line and G line—“I2D/IG”—the density of charge across the graphene layers could be monitored. The obtained results were compared to previous electrical measurements. The substrate longitudinal optical phonon coupling “LOOPC” modes have also been examined for several epitaxial graphene layers. The LOOPC of the SiC substrate shows a precise map of the density of charge in epitaxial graphene systems for different graphene layers number. Correlations between the density of charge and particular graphene layer shape such as bubbles have been determined. All experimental probes show a high degree of consistency and efficiency. Our combined studies have revealed novel capacitor effect in diverse epitaxial graphene system. The SiC substrate self-compensates the graphene layer charge without any external doping. We have observed a new density of charge at the graphene—substrate interface. The located capacitor effects at epitaxial graphene-substrate interfaces give rise to an unexpected mini gap in graphene band structure.

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Preferential carbon etching by hydrogen inside hexagonal voids of 6H-SiC(0001)

Abstract: Characterization of hydrogen etched 6H-SiC(0001) substrates and subsequently grown AlN films

Cited by 16 publications

References 8 publications

Charged nano-domes and bubbles in epitaxial graphene

Charged nano-domes and bubbles in epitaxial graphene

Defect‐selective etching of SiC

Raman Spectroscopy Imaging of Exceptional Electronic Properties in Epitaxial Graphene Grown on SiC

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