First-Principles Study on Layered CN-Metal Interfaces.

Using first-principles calculations, we perform a comprehensive study of representative metal (Al, Sc, Pd, Ag, Pt, and Au) contacts with monolayer (ML) and bilayer (BL) CN, which is a low-cost and easily synthesized two-dimensional metal-free semiconductor. Through analyzing the geometries, electronic structures, and Fermi level pinning effects of CN-metal interfaces, we find metals Al and Sc top contact with ML CN are Ohmic, which can be ascribed to the strong interactions and large orbital overlaps. Besides, owing to weak van der Waals interactions at interfaces and low work functions of metallic materials, Ohmic contacts can also be realized in ML/BL CN-Ag and BL CN-Sc systems. Furthermore, it was also predicted that CN-Sc and CN-Ag systems still maintain Ohmic features along the edge contacts. Given the lower resistance of the Ag electrode, the CN-Ag electrode should be a more attractive electrode in practical applications. These predictions not only provide insights into the fundamental properties of the layered CN-metal interfaces but also pave way to design high-performance devices using low-cost layered CN.