Step control of vicinal 6H-SiC(0001) surface by H_2 etching

摘要

Anisotropic step bunching on vicinal 6H-SiC(0001) surface induced by H_2 etching was investigated. Step structures were observed using atomic force microscopy and high-resolution transmission electron microscopy at off angle <2°. The etched surfaces exhibited three types of step bunching: (1) straight six-bilayer steps, (2) straight six-bilayer steps and nanofacets, and (3) zigzag three-bilayer steps. The step height and density can be controlled by a tilt angle and direction of a vicinal surface. Mechanisms of the step bunching processes are discussed at points of an anisotropy of lateral-etching rates and surface-free energies.