"Our experiment presents an important step towards molecular electronics," ChiiDong Chen of Academia Sinica told nanotechweb.org. "It demonstrates a method for linking gold colloidal particles/C60 nanoparticles/gold electrodes via thiol. Furthermore, it shows that the electric contacts provided by thiol can be modelled as tunnel junctions, and the entire circuit can be analysed in the context of charging effects in multi-island single-electron transistors."
The scientists used electron-beam lithography to form two gold electrodes roughly 160 nm wide, separated by a gap of about 15 nm. These electrodes acted as a source and drain once they were bridged by gold colloidal islands.
To create the electrode-bridging nanoparticles, the researchers alternately applied a solution containing a C60 derivative - formed from a reaction of C60 and 2-aminoethyl propyl disulphide - and a solution containing gold nanoparticles. Repeated applications resulted in the C60 particles attaching to the gold electrodes and then linking one-dimensional chains of gold-colloidal particles separated by C60 molecules to the electrodes. The gold colloidal particles were about 14 nm in diameter.
A gate electrode placed about 400 nm away, meanwhile, was also attached by a chain of C60 and gold nanoparticles and acted as a charge storage cell.
The researchers say that single-electron devices of this type could have applications in the detection and storage of charges, for example detecting excitations such as photons or chemical reactions that cause changes in electric charge. This ability to store charge could reduce power consumption in memory devices.
"Using a similar device scheme, we wish to investigate the transport properties of single-electron transistors containing magnetic particles," added Chen. "Also, if the gap between source-drain leads can be made so small that it contains only one C60 particle [similar to the work by Park et al. reported in Nature but with a different scheme], it would be very interesting to study the transport properties of such a device."
The scientists reported their work in Applied Physics Letters.