Electric Field and Size Effects on Atomic Structures and Conduction Properties of Ultrathin Cu Nanowires

The ballistic transport properties of Cu nanowires (NWs) with diameter of 0.2-1.0 nm under electric field (V = 1 V/angstrom) are reported for future applications as interconnections in microelectronics. Our density-functional calculations show that, under V = 1 V/angstrom, with the wire diameter increasing, the number of conduction channels of a helical atomic strand increases, whereas the number of a nonhelical atomic strand is constant within the considered size range. The structure, electronic, and charge properties of these two types of Cu NWs exhibit distinctly different behaviors.