Solid-state decomposition of silicon carbide for growing ultra-thin heteroepitaxial graphite films

Abstract

Using grazing-incidence x-ray diffraction and scanning tunneling microscopy (STM), we show that the thermal decomposition of an electronic-grade wafer of 6H-SiC after annealing at increasing temperatures TA between 1080 and 1320 °C leads to the layer-by-layer growth of unconstrained, heteroepitaxial single-crystalline graphite. The limited width of the in-plane diffraction rod profiles of graphite reveals large terraces, with an average size larger than 200 Å and a very small azimuthal disorientation. The overlayer is unstrained and adopts the crystalline parameter of bulk graphite even at the smallest coverage studied, which corresponds to a single graphene plane, as inferred from the flat out-of-plane diffraction profile. By increasing TA, additional graphene planes can be grown below this graphite layer from the solid-state decomposition of SiC, forming the AB stacking of Bernal graphite. A C-rich precursor is evidenced in STM by an intrinsic (6×6) reconstruction made of ordered ring or starlike structures. The resulting epitaxial film is indistinguishable from a bulk graphite single crystal.

Ab initiostudy of polarizability and induced charge densities in multilayer graphene films

“…6 These unique features, coupled with the fact that multilayer graphene can be grown and patterned on SiC, provide an important foundation for graphene based electronics. 7 The discovery that an applied electric field induces a band gap in bilayer graphene 6 has generated great interest in the effects of external fields on graphene structures. McCann 8 developed a tight-binding model for bilayer graphene and found a linear relationship between the induced band gaps and induced charges in the bilayer.…”

Visible to vacuum ultraviolet dielectric functions of epitaxial graphene on 3C and 4H SiC polytypes determined by spectroscopic ellipsometry

“…On 4H-Si and 3C-Si, the carbon buffer layer atoms are strongly bonded to the substrate and form a ð6 ffiffi ffi 3 p  6 ffiffi ffi 3 p ÞR30 surface reconstruction, [25][26][27] while on 4H-C, there is no unique surface reconstruction. 28 In our optical model, the interface layer accounts for this buffer layer, and also the roughness of the substrate surface, an effect of the slight off-axis cut of the SiC substrate, and non-uniform sublimation of silicon from the SiC substrate.…”

Highly ordered graphene for two dimensional electronics

“…[7,8,9] These studies showed that graphite grows epitaxially on the (0001) Siterminated (Si-face) surface of SiC, while graphite grown on the C-terminated (0001) (C-face) surface was rotationally disordered and under some conditions formed nanocaps instead of a smooth film. [10] Consequently, the C-face was initially overlooked as a potential substrate for graphene-based electronics.…”

“…The graphite film thickness for all samples was determined by measuring the x-ray intensity as function of ℓ along the graphite (1,1, ℓ) G rod. [8] The notation (h, k, ℓ) G identifies a reciprocal-space point in units of the graphite hexagonal reciprocal lattice basis vectors: a * G = 2.9508 Å −1 and c * G = 1.8829 Å −1 . Unsubscripted reciprocal-space coordinates (h, k, ℓ) refer to the substrate 4H-SiC hexagonal recip- A reciprocal space schematic for epitaxial graphene on SiC is shown in Fig.…”