Formation of epitaxial graphene on SiC(0001) using vacuum or argon environments

Luxmi,; Srivastava, Nishtha; Feenstra, R. M.; Fisher, P.

doi:10.1116/1.3420393

Cited by 26 publications

(42 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…15,16,18 In that case, it is quite easy to produce a single ML extending over 10's or 100's of μm on the surface, with longer annealing (or higher temperatures) presumably leading to a second ML, etc. The contrast between that situation and what we find for the C-face is stark.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Comparison of graphene formation on C-face and Si-face SiC {0001} surfaces

et al. 2010

Self Cite

View full text Add to dashboard Cite

The morphology of graphene formed on the ( 1 000 ) surface (the C-face) and the (0001) surface (the Si-face) of SiC, by annealing in ultra-high vacuum or in an argon environment, is studied by atomic force microscopy (AFM) and low-energy electron microscopy (LEEM). The graphene forms due to preferential sublimation of Si from the surface. In vacuum, this sublimation occurs much more rapidly for the C-face than the Si-face, so that 150°C lower annealing temperatures are required for the C-face to obtain films of comparable thickness. The evolution of the morphology as a function of graphene thickness is examined, revealing significant differences between the C-face and the Si-face. For annealing near 1320°C, graphene films of about 2 monolayers (ML) thickness are formed on the Si-face, but 16 ML is found for the C-face. In both cases, step bunches are formed on the surface and the films grow continuously (carpet-like) over the step bunches. For the Si-face in particular, layer-by-layer growth of the graphene is observed in areas between the step bunches. At 1170°C, for the C-face, a more 3-dimensional type of growth is found. The average thickness is then about 4 ML, but with a wide variation in local thickness (2 -7 ML) over the surface. The spatial arrangement of constant-thickness domains are found to be correlated with step bunches on the surface, which form in a more restricted manner than at 1320°C. It is argued that these domains are somewhat disconnected, so that no strong driving force for planarization of the film exists. In a 1-atm argon environment, permitting higher growth temperatures, the graphene morphology for the Si-face is found to become more layer-by-layer-like even for graphene thickness as low as 1 ML. However, for the C-face the morphology becomes much worse, with the surface displaying markedly inhomogeneous nucleation of the graphene. It is demonstrated that these surfaces are unintentionally oxidized, which accounts for the inhomogeneous growth.

show abstract

Section: Discussionmentioning

confidence: 99%

“…23 From sequences of images acquired at energies varying by 0.1 eV, color-coded maps of the graphene thickness are generated using the method described in Ref. [18].…”

Section: Methodsmentioning

confidence: 99%

Comparison of graphene formation on C-face and Si-face SiC {0001} surfaces

et al. 2010

Self Cite

View full text Add to dashboard Cite

show abstract

“…[12]). 8,9,11 The inelastic effects are seen to significantly diminish the peak-to-valley amplitude of the observed oscillations in the 0 -6 eV range, to a peak-to-valley reflectivity variation of 0.05 for the 6 monolayer (ML) case. We note that the theoretical prediction in Fig.…”

Section: A Free-standing Graphenementioning

confidence: 99%

Inelastic effects in low-energy electron reflectivity of two-dimensional materials

Gao

Mende

Widom

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

View full text Add to dashboard Cite

A simple method is proposed for inclusion of inelastic effects (electron absorption) in computations of low-energy electron reflectivity (LEER) spectra. The theoretical spectra are formulated by matching of electron wavefunctions obtained from first-principles computations in a repeated vacuum-slab-vacuum geometry. Inelastic effects are included by allowing these states to decay in time in accordance with an imaginary term in the potential of the slab, and by mixing of the slab states in accordance with the same type of distribution as occurs in a free-electron model. LEER spectra are computed for various two-dimensional materials, including freestanding multilayer graphene, graphene on copper substrates, and hexagonal boron nitride (h-BN) on cobalt substrates.

show abstract

“…Our experiment employs monolayer-bilayer (ML-BL) interfaces in graphene formed on the Si face of SiC(0001) [13][14][15]. The Si face of SiC allows for better control of the graphene thickness than the C face, due to the Si face initially growing a buffer layer that acts as a template for the graphene formation as the Si is sublimed from the surface.…”

Section: Experiments a Experimental Methodsmentioning

confidence: 99%

Energy Gap Induced by Friedel Oscillations Manifested as Transport Asymmetry at Monolayer-Bilayer Graphene Boundaries

Clark

Zhang

et al. 2014

Phys. Rev. X

View full text Add to dashboard Cite

We show that Friedel charge oscillation near an interface opens a gap at the Fermi energy for electrons with wave vectors perpendicular to the interface. If the Friedel gaps on two sides of the interface are different, a nonequilibrium effect-shifting of these gaps under bias-leads to asymmetric transport upon reversing the bias polarity. The predicted transport asymmetry is revealed by scanning tunneling potentiometry at monolayer-bilayer interfaces in epitaxial graphene on SiC(0001). This intriguing interfacial transport behavior opens a new avenue toward novel quantum functions such as quantum switching.

show abstract

Formation of epitaxial graphene on SiC(0001) using vacuum or argon environments

Cited by 26 publications

References 26 publications

Comparison of graphene formation on C-face and Si-face SiC {0001} surfaces

Comparison of graphene formation on C-face and Si-face SiC {0001} surfaces

Inelastic effects in low-energy electron reflectivity of two-dimensional materials

Energy Gap Induced by Friedel Oscillations Manifested as Transport Asymmetry at Monolayer-Bilayer Graphene Boundaries

Contact Info

Product

Resources

About