Nano-dots array whose diameter and interval were approximately 200 nm and 750 nm, respectively, were made parallel to the atomic step edges on sapphire wafers by focused ion beam (FIB) system. Upon annealing a bunched multi-steps structure formed at regularintervals and straight because the steps were pinned at the nano-dots. The step heights andterrace widths were approximately 2.0 nm, 700 nm in off-angle 0.15° and 10.0 nm, 350 nm in off-angle 1.0°, respectively.
