This page has moved. Please update your links. If you are not redirected in 10 seconds
please click here
http://www.phys.canterbury.ac.nz/research/nano/deposition.shtml
Deposition of Atomic Clusters
We have recently begun a new project on the fabrication of nano-electronic
devices by deposition of clusters. This work is partially funded by NERF.
Nanowires from Atomic Clusters
In general, there a two distinct approaches to fabricating nanoscale devices:
‘top-down’ and ‘bottom up’. In the ‘top-down’ approach, devices are created
by a combination of lithography and etching. These are highly developed
and reliable technologies, but the current state-of-the-art can achieve
devices with dimensions ~10nm only at great expense. The ‘bottom-up’ approach
proposes the assembly of devices from nanoscale building blocks, thus immediately
achieving nanoscale resolution, but suffers from a range of other problems,
including the difficulty, expense, and long time periods that can be required
to assemble the building blocks.
A key question is whether or not the top-down and bottom-up approaches
can be combined to fabricate devices which take the best features of both
approaches while circumventing their inherent problems. We have recently
been able to do exactly that: we have incorporated nanoscale clusters into
electronic devices with nanoscale overall dimensions.
Percolating Cluster Assembled Nanodevices
A schematic illustration of a cluster-based nanowire.
One of the merits of our technique is that it is extremely simple: nanoscale
particles, formed by inert gas aggregation, are deposited from a molecular
beam onto prefabricated lithographically defined nanocontacts. The cluster
deposition is random but can be understood within percolation theory. By
developing a deep understanding of the theory, and using sophisticated
computer simulations, we have designed device geometries that ensure a
single wire-like path is formed between the contacts near the percolation
threshold. An electrically conducting nanowire, which is automatically
connected to electrical contacts, is therefore formed with no need
to manipulate particles individually, or to use complex fabrication techniques.
The width of the wire can be controlled by the size of the deposited particles.
Schematic of our experimental arrangement for cluster deposition
between a pair of electrical contacts.
Further work
The work described above was originally intended as a first attempt to
fabricate cluster deposited films with nanoscale dimensions, and to develop
the technologies required for fabrication of a series of more complex devices.
Work on these devices is now underway, as is an effort to comprehensively
characterise the properties of percolating cluster films.
Templated Cluster Assembled Nanodevices
We have recently been able to produce our first devices using a new templating
technology to allow assembly of clusters into working devices. Further
details will be available after publication of this work.
A Field Emission SEM image of a Templated Cluster Assembled
Nanowire, approximately 100nm in width at its smallest point.
Other relevant pages:
Deposition
of Sb and Bi onto HOPG
Structure
of atomic clusters
Some
other information about clusters