Abstract: N-wells are created by P+ ion implantation into Si-faced p-type 4H-SiC epilayer.Ti and Ni are deposited in sequence on the surface of the active regions.Ni2Si is identified as the dominant phase by X-ray diffraction (XRD) analysis after metallization annealing.An amorphous C film at the Ni2Si/SiC interface is confirmed by an X-ray energy-dispersive spectrometer (XEDS).The Ni2Si and amorphous C film are etched away selectively,followed by deposition of new metal films without annealing.Measurement of the current-voltage characteristics shows that the contacts are still ohmic after the Ni2Si and amorphous C film are replaced by new metal films.The sheet resistance Rsh of the implanted layers decreases from 975 to 438Ω/□,because carbon vacancies (VC) appeared during annealing,which act as donors for electrons in SiC.

Key words: Ni, ohmic contact, silicon carbide, carbon vacancies, P+ ion implantation