Structural properties of the graphene-SiC(0001) interface as a key for the preparation of homogeneous large-terrace graphene surfaces

Abstract

We report on the interface between graphene and 4H-SiC͑0001͒ as investigated by scanning tunneling microscopy ͑STM͒ and low energy electron diffraction ͑LEED͒. It is characterized by the so-called ͑6 ͱ 3 ϫ 6 ͱ 3͒R30°reconstruction, whose structural properties are still controversially discussed but at the same time are crucial for the controlled growth of homogeneous high-quality large-terrace graphene surfaces. We discuss the role of three observed phases with periodicities ͑6 ͱ 3 ϫ 6 ͱ 3͒R30°, ͑6 ϫ 6͒, and ͑5 ϫ 5͒. Their LEED intensity levels and spectra strongly depend on the surface preparation procedure applied. The graphitization process imprints distinct features in the STM images as well as in the LEED spectra. The latter have the potential for an easy and practicable determination of the number of graphene layers by means of LEED.

Spatially Resolved Mapping of Electrical Conductivity across Individual Domain (Grain) Boundaries in Graphene

“…2,23 Figure 1b is the STM image of a boundary between monolayer (ML) and bilayer (BL) graphene, clearly showing moiré pattern and atomic lattice of graphene with a background due to the   30 ) 3 6 3 6 ( R reconstructed buffer layer. 24 The BL graphene appears much smoother than the ML. Because the graphene layer is formed through the graphitization of SiC (0001), a ML-BL boundary almost always coincides with an underlying substrate step.…”

Raman spectroscopy and imaging of graphene

“…The structure of EG was confi rmed by in situ low energy electron diffraction (LEED), STM, and photoemission spectroscopy (PES) [76]. Since the characteristic STM images of carbon nanomesh and single layer graphene are quite different, the appearance of single layer EG can be detected by monitoring the phase evolution from carbon nanomesh to graphene by in situ STM during the thermal annealing of SiC [76,79]. However, the STM images for single layer and bilayer EG on SiC are very similar.…”

Step-edge-induced resistance anisotropy in quasi-free-standing bilayer chemical vapor deposition graphene on SiC

“…[56][57][58] It can be decoupled to form a quasi-freestanding bilayer graphene (QFS-bilayer) through hydrogen atoms intercalation. 59 The intercalating atoms diffuse underneath the buffer layer and bound themselves to the topmost Si atoms of the SiC substrate converting the buffer layer to a mostly sp2-hybridized monolayer graphene.…”