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.

Phase contrast images of dislocation micropipe in SiC crystal are experimentally studied at various distances from the sample using synchrotron white beam. Computer simulation of these images enabled us to understand the peculiarities of image formation and measure the diameter of the micropipe. The phase contrast imaging of micropipes without monochromator is explained by the absorption of x rays in a thick (490μm) SiC crystal, effectively forming a high brilliance radiation spectrum with a pronounced maximum at 16keV.

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