"Importantly, the same approach can be applied to large-scale and parallel synthesis of other nanoscale devices/sensors containing elements such as nanowires, carbon nanotubes and nanoparticles," Koh told nanotechweb.org. "The lack of such techniques until now has been one of the main obstacles limiting the widespread, practical application of these devices."
CMOS fabrication techniques
Koh's team made its devices using well established CMOS fabrication techniques, including photolithography, thin-film deposition and etching. The secret behind the new procedure is to stack two electrodes, which contain a thin layer of insulation between them, and attach gold nanoparticles on the exposed side of the stack via self-assembled monolayers.
Until now, single-electron device fabrication required sophisticated nanoscale pattern definition, such as e-beam lithography, nano-oxidation using STM/AFM, mechanically controlled break junctions and electromigration. However, these techniques are not suitable for large-scale parallel processing.
"Our study shows that chip-level fabrication of single-electron devices is possible using conventional CMOS fabrication technology without resorting to complicated procedures," explained Koh. This suggests a paradigm shift in the way that single-electron devices (and possibly many other nanoscale architectures) are made.
Advantages of single-electron devices
Single-electron devices have many advantages over conventional electronic devices, including the fact that they consume very little power and can operate in the sub-nanometre regime (which means that many devices can be packed into an extremely small space). "Such properties could benefit a variety of applications, including commercial electronics and military and space applications," said Koh.
Now that parallel fabrication of nanoscale devices appears feasible, it should be relatively straightforward to build integrated systems of single-electron transistors much like the way in which current CMOS devices are made, adds Koh. The team's next goal is to make single-electron memories and then logic systems. In such devices, 1s and 0s can be represented by the presence or absence of just a few single electrons.
The researchers reported their work in Nature Nanotechnology.