Epitaxial graphene on SiC is an exciting new electronic material that presents the possi- bility of room temperature ballistic devices. 6–8 Extremely high carrier mobilities, exceeding 250,000 cm $^{2}$/(V · s) at room temperature, have been observed, 9 and epitaxial graphene has been shown to be compatible with traditional top-down processing techniques. 10 Its linear semi-metallic band structure 11 allows ambipolar tuning of conduction and direct application to RF devices, 12 while other devices require modification of the graphene sheet to induce a band gap. The latter has received significant attention, and has been accomplished by selective chemical treatment, 13,14 and nanoribbon fabrication, 1–5 which results in a band gap inversely proportional to ribbon width. 15–17 The nanoribbon approach is promising in that it has shown large gating effects, but production methods documented thus far, including e-beam lithography 1–3 and other approaches, 4,5 are too slow and not controllable enough for technological application. 

Morphology of epitaxial graphene on SiC is highly influenced by the structure of the underlying substrate. In well-controlled growth conditions, 7,8,18,19 nominally on-axis SiC re- tains an ordered terrace structure that originates in the miscut angle of the SiC wafer. Many interpret these steps as being problematic, 20 but scanning tunneling microscopy measure- ments have consistently observed that the graphene lattice is continuous over such steps. This is true of 0 . 5 nm 4 H -SiC half-unit cell steps and few-nm steps where step bunching occurs. 6,21 We find [see Fig. 1] that this remains true at a much larger scale; graphene pleats typically present on the SiC(000 ¯ 1) plane 18 are observed traversing prepared SiC steps as large as 150 nm, indicating continuity of graphene over the step. These observations ex- plain transport measurements in which underlying SiC steps appear to have little effect on mobility 7,22 or observation of the quantum Hall effect, 22 and suggest exploitation of the effect to produce nanoribbons by novel fabrication methods. 

It has long been known 23 that SiC { 0001 } surfaces exhibit step bunching in various envi- ronments. Recent systematic studies have found a greater propensity for step bunching on the (0001) face, 24–27 with vicinal miscuts toward 〈 1 ¯ 100 〉 displaying bunching of parallel steps into (1 ¯ 10 n ) “nanofacets” up to 4 − 5 unit cells in height, oriented at an angle of ∼ 25 ◦ to the basal plane. 25,26 It has been suggested that such nanofacet formation may be understood as a minimization of surface free energy. 25,28 Steps perpendicular to the directions 〈 1 ¯ 100 〉 are strongly favored on (0001), such that steps formed macroscopically perpendicular to 〈 11 ¯ 20 〉 are microscopically zigzagged, with segments perpendicular to 〈 1 ¯ 100 〉 directions. 24–27 

