NONLITHOGRAPHIC NANO-WIRE ARRAYS - FABRICATION, PHYSICS, AND DEVICE APPLICATIONS

A novel system of nanostructures is described consisting of nonlithogr aphically produced arrays of nano-wires directly electrodeposited into porous anodic aluminum oxide templates. Using this method regular and uniform arrays of metal or semiconductor nano-wires or nano-dots can be created with diameters ranging from similar to 5 nm to several hund red nanometers and with areal pore densities in the similar to 10(9)-1 0(11) cm(-2) range. We report on the present state of their fabricatio n, properties, and prospective device applications. Results of X-ray d iffraction, Raman and magnetic measurements on metal (Ni, Fe) and semi conductor (CdS, CdSe, CdSxSe1-x, CdxZn1-xS and GaAs) wires are present ed. The I-V characteristics of two terminal devices made from the nano -arrays are found to exhibit room temperature periodic conductance osc illations and Coulomb-blockade like current staircases. These observat ions are likely associated with the ultra-small tunnel junctions that are formed naturally in the arrays. Single-electron tunneling (SET) in the presence of interwire coupling in these arrays is shown to lead t o the spontaneous electrostatic polarization of the wires. Possible de vice applications such as magnetic memory or sensors, electroluminesce nt flat-panel displays, and nanoelectronic and single-electronic devic es are also discussed.