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 ( 0 0 0 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 (0 0 0 1) surface produce full unit-cell high steps, while half unit-cell high steps are observed on the ( 0 0 0 1 ¯ ) surface. The observed step normal direction is found to be 〈 1 1 ¯ 0 0 〉 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 〈 1 1 2 ¯ 0 〉 direction. For (0 0 0 1) vicinal surfaces that are miscut towards the 〈 1 1 ¯ 0 0 〉 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 ( 0 0 0 1 ¯ ) surfaces. Additionally, the (0 0 01) surface is found to have a much larger spatial anisotropy in step energies than the ( 0 0 0 1 ¯ ) surface.