Characterization and modeling of twinning superlattice structure in copper nanowires

Copper metallization with dense nanoscale coherent twin boundaries (CTBs) have demonstrated many spectacular properties that are generally curtailed by the CTB spacing. In this study, electroplated Cu nanowires (CuNWs) with pseudo periodic twinning structures were experimentally characterized by high resolution transmission electron microscopy. The variation of electron diffraction pattern (EDP) with different CTB spacing is modeled using a non-primitive hexagonal cell in which the closest packed atomic layers stack along the c-axis. The modeled EDPs were found to agree with the experimentally recorded EDPs for three different twinning superlattice structures in the CuNWs. The study shall help identify the EDP fine feature induced by twinning superlattice structure in nanotwinned metallization.