Structural and electronic properties of SiC nanotubes filled with Cu nanowires: A first-principles study

The structural and electronic properties of Cun (n=5,9,13) nanowires encapsulated in armchair (8,8) silicon carbon nanotubes (SiCNTs) are investigated using the first principles calculations within the generalized-gradient approximation. We find that the formation processes of these systems are all exothermic. The initial shapes (quadratic–prismatic Cu wire and cylindrical (8,8) SiCNT) are preserved without any visible changes after optimization for the Cu5@(8,8) and Cu9@(8,8) combined systems, but a quadratic-like cross-section shape is formed for the outer nanotube of the Cu13@(8,8) combined system due to the stronger interaction between nanowire and nanotube. The electrons for Si and C atoms in outer SiC sheath affect the electron conductance of the encapsulated metallic nanowire in the Cu13@(8,8) combined system. But in the Cu5@(8,8) and Cu9@(8,8) combined systems, the conduction electrons are distributed only on the copper atoms, so electron transport will occur only through the inner Cu nanowires and the outer inert SiCNTs only function as insulating cable sheaths. Considering the maximal metal filling ratio in nanotube, we know that the Cu9@(8,8) combined system is top-priority in the ultra-large-scale integration (ULSI) circuits and micro-electromechanical systems (MEMS) devices that demand steady transport of electrons.