Sheathed nanowires aligned by crystallographic periodicity: a possibility of cross-bar wiring in three-dimensional space
Because of the translational symmetry of crystal structures, crystal engineering may provide an opportunity for developing a three-dimensional and large-scale molecular memory array that is wired by sheathed nanowires with a cross-bar configuration, once a certain extent of designability is accomplished. This article discusses crystal structures involving ordered nanowire arrays that might be used for such a purpose. Some crystallographic symmetries and conduction/insulation properties required for wiring application are described, followed by the description of the structural and conducting properties of known sheathed nanowires with crystalline periodicity. The wires discussed here are made of wide range of materials including metal atoms, polymers, and organic radical species. Although most of the nanowire crystals show parallel alignments of the sheathed nanowires, several examples show cross-bar arrangements.