Study of Copper Nanowires With Five-Twinned Structure Grown by Chemical Vapor Deposition and Their Applications

Abstract

Free standing CuNWs were grown by chemical vapor deposition using a copper precursor, Cu(etac)[P(OC2H5)3] 2. The CuNWs have a five-fold twinned crystalline structure with five {100} side planes and a pentagonal pyramid tip formed by five {111} planes. The electron diffraction pattern disclosed that the twin boundaries are mismatched irregularly. The internal stress could be relaxed by the defect generation in one of the five subcrystals and the displacement of the pentagonal axis of the nanowire. The growth mechanism for the 1-dimensional CuNW-growth is proposed to be the passivation by the phosphite, acting as a capping agent dissociated from the precursor, on {100} side planes of the CuNWs. CuNWs by CVD could also be selectively grown on a patterned Au/Si substrate. Single CuNW was selectively grown on the nanoscale-patterned substrate. Selectivity was achieved with the aid of phosphite passivation of the gold surface. The temperature dependent growth of CuNWs confirmed the role of phosphite on 1-dimensional growth of nanowires. The selectively grown CuNWs could serve as practical and promising interconnects for nanoscale devices. The electron emission characteristics of CuNWs were investigated, indicating that the CuNWs are a promising electron emitter. An array of CuNWs grown on a patterned silicon substrate was used in a proof-of-principle experiment to demonstrate a CuNW-based field emission display device. Due to their sharp tips and controlled growth, the CVD-grown CuNWs may prove to be useful for field emission arrays. The optical properties of CuNWs were measured and verified by the discrete dipole approximation (DDA) simulation. The optical tunability of the CuNWs with respect to the aspect ratio might enable us to use their optical characteristics as optical modulating tools or optical filters.