Ohmic contacts on silicon carbide: The first monolayer and its electronic effect

We demonstrate that origin of the long-standing contact issue in silicon carbide devices can be understood and technologically manipulated at the atomic level. Using advanced transmission electron microscopy, we attribute qualitatively the formation of ohmic contacts to silicon carbide to an epitaxial, coherent, and atomically ordered interface. Quantitatively, first-principles calculations predict that this interface can trap an atomic layer of carbon and hence enable lowered Schottky barrier and enhanced quantum electron transport. The combined experimental and theoretical studies performed provide insight into the complex electronic and electric effects of the buried contact interface, which are fundamental for improving the contact in future electronics based on wide-band-gap semiconductors such as silicon carbide and diamond.