Step formation on hydrogen-etched 6H-SiC{0001} surfaces

摘要

The formation of step bunches and/or facets on hydrogen-etched 6H-SiC(0001) 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 (0001) 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 (1100) 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 (1120) direction. For (0001) vicinal surfaces that are miscut towards the (1100) 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 (0001) surface is found to have a much larger spatial anisotropy in step energies than the (0001) surface.