Large Discrete Resistance Jump at Grain Boundary in Copper Nanowire

Copper is the current interconnect metal of choice in integrated circuits. As interconnect dimensions decrease, the resistivity of copper increases dramatically because or electron scattering from surfaces, impurities, and grain boundaries (GBs) and threatens to stymie continued device scaling. Lacking direct measurements of individual scattering sources, understanding of the relative importance of these scattering mechanisms has largely relied on semiempirical modeling. Here we present the first ever attempt to measure and calculate individual GB resistances in copper nanowires with a one-to-one correspondence to the GB structure. Large resistance jumps are directly measured at the random GBs with a value far greater than at coincidence GBs and first-principles calculations. The high resistivity of the random GB appears to be intrinsic, arising from the scaling of electron mean free path with the size of the lattice relaxation region. The striking impact of random GB scattering adds vital information for understanding nanoscale conductors.X116562sciescopu

Structural Dependence of Grain Boundary Resistivity in Copper Nanowires

We report the direct measurement of individual grain boundary (GB) resistances and the critical role of GB structure in the increased resistivity in copper nanowires. By measuring both intra-and inter-grain resistance with a four-probe scanning tunneling microscope, large resistance jumps are revealed owing to successive scattering across high-angle random GBs, while the resistance changes at twin and other coincidence boundaries are negligibly small. The impurity distributions in the nanowires are characterized in correlating to the microstructures. The resistance of high symmetry coincidence GBs and the impurity contributions are then calculated using a first-principle method which confirms that the coincidence GBs have orders of magnitude smaller resistance than the high-angle random GBs. (C) 2011 The Japan Society of Applied PhysicsX113sciescopu

Investigation of Pitting Corrosion in Sensitized Modified High-Nitrogen 316LN Steel After Neutron Irradiation

The influence has been studied of thermo-mechanical treatment, sensitization conditions, and neutron irradiation on the pitting corrosion resistance of austenitic 316LN stainless steel variants in 10% FeCl[subscript 3]·6H[subscript 2]O at 22 °C. Variants of this steel were modified with additions of nitrogen, manganese, copper, and tungsten, as well as testing cast, cold-rolled, grain boundary engineered (GBE), and as-received variants. It was found that the 316LN steel variant with additions of 0.2% N and 2% Mn had the best pitting corrosion resistance of all studied conditions. When irradiated in a light water reactor (LWR) to a maximum fluence of 3 × 1017 n/cm[superscript 2] (E > 1.1 meV, Tirr < 50 °C), neutron irradiation surprisingly increased the resistance of GBE steels to pitting corrosion. An anisotropy of corrosion resistance of GBE and cold rolled steels was observed. Keywords: Austenitic stainless steel, Alloying, Nitrogen, Tungsten, Copper, Sensitization, Pitting corrosion, Grain boundary engineerin