R&D
for growing conducting polymers called Surface Polymerisation of
Ion-Assisted Deposition or SPIAD (Journal of the American Chemical Society,
online since February 6 and in print March 5, 2003).
The project leader Luke Hanley reports: "Basically, the way it works is you
have a surface upon which you want to grow a thin film. You put that into a
vacuum chamber, pump all the air out, and you simultaneously deposit charged
ions on to the surface and evaporate neutral molecules onto the surface.
These ions and neutrals meet at the surface and form this continuous
polymeric film."
He adds: "Weve been able to show we can control the chemistry and shape of
the surface on a nanometre scale. It allows you to control what this thin
film is on the sub-nanometre scale."
Initial experiments with thiophene ions failed to produce a conducting
polymer called polythiophene as hoped. They "formed something" but Hanley
says "it wasn an interesting polythiophene. So we brought in both an ion
beam and neutral beam at the surface."
Hanley modified a commercial ion source to work with organic material such
as thiophene. "We can put organic molecules into it and get out the types of
ions that we want. We can actually grow large areas of films fairly quickly
by this method. We e not quite at manufacturing scale yet, but weve
demonstrated that we know how to get to that point."
The groups is now exploring different properties of other films using the
technique with hopes for creating a whole class of conducting polymers.
Scientists at the California Institute of Technology claim to have increased
the Q-factor for chip-based optical resonators by nearly four orders of
magnitude (Nature, February 27, 2003). Optical resonators consist of
cavities that can trap light for a certain length of time given by the
Q-factor. The measured Q for the new structures was in excess of 100mn.
The Caltech cavities were fabricated on silicon wafers with a 2micron thick
layer of silicon dioxide (silica). First, disk-shaped circular 160micron
diameter photoresist pads are formed on the SiO2 using standard lithography.
A bake process was then used to smooth the edges of the pad. The pads are
then used as a mask in an HF etch of the SiO2 and the photoresist is then
removed. A XeF2 dry etch is then used to cut into the silicon but not the
oxide.
The result is silicon pillars with silica caps. The periphery of the silica
cap contains the resonant light paths. Undercutting the caps inhibits photon
leakage from these paths. Additional heat and reflow processing with a CO2
laser is used to improve the surface finish of the silica disks creating a
toroid-like structure at the edge.
What started as research into transistor reliability could lead to a new
silicon chip based "nano-lamp". A scientist at Netherlands University of
Twente, Phuong Le Minh, found that a controlled breakdown in semiconductor
oxide layers of the transistor/antifuse structure of memory cells can emit
light. Le Minh has focused his research on mircofluidic applications. A
lightsource and photodetector has been integrated with a micron-sized
channel. The set up is able to distinguish the various fluids in the
channel. By looking for interference patterns, information about the fluid
can be obtained. The research has been part of Le Minhs PhD work at the
universitys MESA+ research institute.
Concrete results from the European Commissions nanotechnology projects from
the Fifth Framework (FP5) programme have been put up on the Commissions
Research and Development Information Service (CORDIS) website.
The nanotechnology thematic service offers direct and central access to
information on funding opportunities, both at European and national level,
project descriptions, publications and surveys, as well as network details.
Potential participants in the ECs Sixth Framework Programme (FP6) are
invited to inspect the site. The preliminary budget for nanotechnology and
nanoscience projects amounts to EUR1.3bn.
http://www.cordis.lu/nanotechnology/home.html
