Step Formation on Hydrogen-etched 6H-SiC{0001} Surfaces

The formation of step bunches and/or facets on hydrogen-etched SiC (0001) and (000-1) surfaces has been studied, using both nominally on-axis and intentionally miscut (i.e. vicinal) substrates. It is found that small miscuts on the (0001) surface produce full unit-cell high steps, while half unit-cell high steps are observed on the (000-1) surface. The observed step normal direction is found to be <1-100> 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 <11-20> direction. For (0001) vicinal surfaces that are miscut towards the <1-100> 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 (000-1) surfaces. Additionally, the (0001) surface is found to have a much larger spatial anisotropy in step energies than the (000-1) surface.