Ohmic contact behaviour of Co/C/4H-SiC structures

The electrical contact properties of Co/4H-SiC structures are investigated.A carbon interfacial layer between a Co film and SiC is used to improve the Ohmic contact properties significantly.The C film is deposited prior to Co film deposition on SiC using DC sputtering.The high quality Ohmic contact and specific contact resistivity of 2.30×10;Ω·cm;are obtained for Co/C/SiC structures after two-step annealing at 500℃for 10 min and 1050℃for 3 min.The physical properties of the contacts are examined by using XRD.The results indicate that the Co-based metal contacts have better structural stability of silicide phases formed after the high temperature annealing and carbon-enriched layer is produced below the contact,playing a key role in forming an Ohmic contact through the reduction of effective Schottky barrier height for the transport of electrons.The thermal stability of Au/Co/C/SiC Ohmic contacts is investigated.The contacts remain Ohmic on doped n-type(2.8×10;cm;) 4H-SiC after thermal aging treatment at 500℃for 20 h.