A structural study of SiC layers grown by molecular beam epitaxy on carbonized Si(I 11) substrates with Ge modified interfaces is reported. Different quantities of Ge were predeposited prior to the SiC growth for comparison. X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy in both conventional (CTEM) and high-resolution modes (HREM) and selected-area electron diffraction (SAED) have been used to evaluate the structural quality of the SiC layers. SIMS measurements show that, after the epitaxial growth, the predeposited Ge remains at the interface and in the region of the silicon substrate closest to the interface. This observation was confirmed by HREM investigations. The 300 rim-thick SiC layers are subject to a residual in-plane tensile strain of 0.7-0.8%. The defect structure indicates an enhanced lattice relaxation caused by Ge incorporation into the SiC/Si interface. The grain size tends to decrease as Ge coverage increases. Furthermore, the presence of Ge suppresses the formation of voids at the interface thanks to the formation of a Si/Ge/C alloy interlayer acting as a barrier for the outdiffusion of Si.