Thermal conductivity and electrical resistivity of single copper nanowires†
Copper nano-interconnects are ubiquitous in semiconductor devices. The electrical and thermal properties of copper nanowires (CuNWs) profoundly affect the performance of electronics. In contrast to the intensively studied electrical properties of CuNWs, the thermal conductivities of CuNWs have seldom been examined. In this study, the electrical resistivity and thermal conductivity of single CuNWs were investigated. The Bloch–Grüneisen formula was introduced to determine the mechanisms responsible for the obtained electrical resistivity of the CuNWs. High residual resistivity was found, which indicated strong structural scattering on the electron transport resulting from defect scattering and boundary scatterings at the copper–copper oxide interface and grain boundaries. The mean structural scattering distance was employed to appreciate the degree of structural scattering in the CuNWs. The residual resistivity and electron–phonon coupling parameter were found to increase with the degree of structural scattering. Moreover, the unified thermal resistivity was introduced to illustrate the mechanisms responsible for the CuNWs’ thermal conductivities. Similarly, large values of residual unified thermal resistivity and electron–phonon-induced unified thermal resistivity were found. The obtained unified thermal resistivities of the CuNWs could also be qualitatively explained by the degree of structural scattering in the CuNWs. The results suggested that structural scattering was predominant in the electrical current transport and heat transfer in the nanowires. This study revealed the mechanisms of electrical resistivity and thermal conductivity of CuNWs, and the insights could assist in improving the design of semiconductor architectures.