The atomic arrangement on SIC surfaces appears to have a direct relation to technological applications with respect to oxidation, crystal growth and polytype development. Ex situ hydrogen treatment leads to an epitaxially well matching silicon oxide monolayer on both SiC(0001) and (000(1) over bar) which promises to allow deposition of low defect density oxide films for MOS devices. The extremely efficient dangling bond saturation on SiC(0001)-(3x3) facilitates step flow growth for monocrystalline homoepitaxial layers. A (root 3x root3)R30 degrees phase on SiC(0001) is characterized by a Si adatom in a so-called T4 site. By modifying the preparation condition of this phase the layer stacking in the outermost surface slab can be influenced on hexagonal 4H and 6H samples. This might serve as seed for polytype heterojunctions. A modified stacking can also be obtained below the H3 adatoms of a (2x2) Chase on SiC(000(1) over bar).