The present document discloses a semiconductor device structure (1) comprising a SiC substrate (11), an Inx1Aly1Ga1-x1-y1N buffer layer (13), wherein x1=0-1, y1=0-1 and x1+y1=1, and an Inx2Aly2Ga1-x2-y2N nucleation layer (12), wherein x2=0-1, y2=0-1 and x2+y2=1, sandwiched between the SiC substrate (11) and the buffer layer (13). The buffer layer (13) presents a rocking curve with a (102) peak having a FWHM below 250 arcsec, and the nucleation layer (12) presents a rocking curve with a (105) peak having a FWHM below 200 arcsec, as determined by X-ray Diffraction (XRD).Methods of making such a semiconductor device structure are disclosed.