Growth and electrical characterization of thin conductive Au nanoparticle chains on oxidized Si substrates between electrodes for sensor applications

摘要

Citrate-stabilized colloid Au nanoparticlcs with an average diameter of 40 nm have been assembled in nanopartiele chains between microelectrodes on oxidized V-groove-etched Si surfaces by the technique of dielectrophoresis. Chain formation was investigated as a function of electrodes configuration and the amplitude and frequency of the applied electric field. Conductive thin (～100-200 nm thick) single and multiple Au nanoparticle chains, with a length in the range of 1 to 10 μm, were preferentially formed on V-groove lines between the electrodes. Electrical characterization by temperature-dependent current-voltage measurements showed that the Au nanoparticle chains exhibit ohmic conductivity with a resis-rntance in the range of few Ω to few kΩ, depending on the distance between electrodes and the configuration of the Au nanoparticlcs in the structure. On the contrary, 5 nm diameter tiopronin-stabilized Au NPs chains exhibited nearest-neighbour hopping conductivity and non-linear thermally-activated I-V characteristics. We also tested nanogap formation in the chains by an applied pulse of electric current, in view of applying the nanoparticle chains in the tracing of chemical or biological molecules. The conductive thin Au nanoparticle chains, with or without nanogaps, are interesting building blocks for different sensor devices.