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

The formation of step bunches and/or facets on hydrogen-etched 6H-SiC(0001) and (000 (1) over bar) 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) over bar) surface. The observed step normal direction is found to be (1 (1) over bar 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 (11 (2) over bar0) direction. For (0001) vicinal surfaces that are miscut towards the (1 (1) over bar 00) direction, the formation of surface ripples is observed for 31 miscut and the development of small facets (nanofacets) is found for higher miscut angles. Much less faceting is observed on miscut (000 (1) over bar) surfaces. Additionally, the (0001) surface is found to have a much larger spatial anisotropy in step energies than the (000 (1) over bar) surface. (C) 2008 Elsevier B.V. All rights reserved.