After high-temperature ${\mathrm{H}}_2$ etching, vicinal SiC(0001) surfaces showed periodically ordered nanofacet structures consisting of pairs of (0001) and $(11\overline{2}n)$. Here, we found that the characteristic ordering distance of $\sim 10\mathrm{nm}$ is independent of the vicinal angle (4°–8° off). However, fluctuation in the ordering distance is dependent on the vicinal angle. The 5.7° off surface showed superior periodicity. The classical elastic theory of a surface predicted the characteristic (constant) ordering distance but not the fluctuation in ordering periodicity. By introducing “quantized step bunching” due to periodic surface energy, which is unique to polymorphic SiC, the fluctuation is described.

• Received 6 March 2007

DOI:https://doi.org/10.1103/PhysRevLett.99.016102