Fabrication of ohmic contact on the carbon-terminated surface of n-type silicon carbide

Abstract

A set of Au/Ti/Ni/Ge metallizations with different thicknesses of the underlying titanium layers have been deposited on the carbide-terminated face of n-type silicon carbide (SiC) to get low ohmic contact resistance. The electrical and microstructural properties of the contacts are studied. It is observed that the conducting behavior of all samples is rectifying after annealing at 800°C and becomes ohmic after annealing above 850°C in vacuum atmosphere. Titanium shows smaller contact resistance for the carbon face of n-type SiC than other metal layers. The specific contact resistance is investigated by Transfer Line Method (TLM) measurements. The contact resistivity of sample Au/Ti/SiC exhibits unmonotonous dependence with the thickness of titanium. The best specific contact resistance is 2.02×10−5Ωcm2. High resolution X-ray diffraction analysis results indicate that carbon atoms release from the surface of C-face of SiC and interact with titanium atoms to form titanium carbide (TiC) at the contact surface.