Fabricating gold nanobridges between gold nanoelectrodes using dielectrophoresis technique

Dielectrophoretic assembly of gold (Au) nanoparticles in nanogap electrodes to fabricate continuous nanobridges is reported. Dielectrophoresis (DEP) process involves the optimization of three parameters: peak-to-peak voltage (V_pp), frequency, and time. The complete and reliable assembly of nanoparticles in the nanogap electrodes require optimization of these parameters. Frequency optimization from few kHz to 1 MHz led to the observation of wide variety of assembly in between the nanogap electrodes. The other DEP parameters such as voltage and time had their own influence on assembling the nanoparticles in nanogap electrodes. It was found that a frequency of 150 kHz, V_pp~ 3.5 V and time of 3 s led to the creation of nanobridge assembly in nanogap electrodes (60 nm). Time parameter was varied from 1 to 5 s, and nanobridges of different types i.e. discrete (consisting of Au nanoparticles connected to each other) and continuous (a continuous Au segment completely bridging the nanogap electrodes) were fabricated. Current-voltage characteristics showed the continuous nanobridged electrodes were exhibiting ohmic behavior. Such devices could be used to perform electromigration to fabricate sub-nanogap electrodes to realize devices for molecular electronics.