Step Formation on Hydrogen-Etched 6H-Sic{0 0 0 1} Surfaces

Abstract

The formation of step bunches and/or facets on hydrogen-etched 6H-SiC(0 0 0 1) and (0001¯) surfaces has been studied, using both nominally on-axis and intentionally miscut (i.e. vicinal) substrates. It is found that small miscuts on the (0 0 0 1) surface produce full unit-cell high steps, while half unit-cell high steps are observed on the (0001¯) surface. The observed step normal direction is found to be 〈11¯00〉 for both surfaces. Hence, for intentionally miscut material, a miscut oriented towards this direction produces much better order in the step array compared to a miscut oriented towards a 〈112¯0〉 direction. For (0 0 0 1) vicinal surfaces that are miscut towards the 〈11¯00〉 direction, the formation of surface ripples is observed for 3° miscut and the development of small facets (nanofacets) is found for higher miscut angles. Much less faceting is observed on miscut (0001¯) surfaces. Additionally, the (0 0 01) surface is found to have a much larger spatial anisotropy in step energies than the (0001¯) surface.