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Abstract:
The basal surfaces of hexagonal SiC exhibit a large variety of surface
reconstructions that develop under a similarly rich variety of sample
preparations. A subset of these surface phases, which have been
investigated in structural detail using scanning tunnelling microscopy
and quantitative low-energy electron diffraction, is described and
shown to offer the scope to be used for the formation of SiC-based
semiconductor devices. The phases discussed are the (3 x 3) and (root3
x root3)R30degrees reconstructions for the (0001) surfaces of 4H- and
6H-SiC and the oxygen-uptake-driven (root3 x root3)R30degrees-SiOX
reconstructions of these polytypes for both the (0001) and the (000 (1)
over bar) surface orientations. We show that the (3 x 3) reconstruction
corresponds to a highly passivated surface that facilitates hexagonal
single-crystal growth, while Suitable preparation of the (root3 x
root3)R30degrees reconstruction favours a switch to cubic growth and
hence to the formation of a heterojunction. The (root3 x
root3)R30degrees-SiOX reconstructions promise to form defect-free
interfaces to insulating silicon oxide films, which is important for
device applications.
