3C-SiC was grown by carbonization on (111)Si by solid source molecular beam epitaxy at 750 degreesC. The use of additional Ge deposition before or during carbonization leads to a lowering of the SiC growth rate in a different way at the beginning of the growth process, which was obtained by real time spectroscopic ellipsometry and real time RHEED. Ge is mainly incorporated at the SiC/Si interface and causes an increase of the SiC grain diameter independent on the incorporation method.