 Metal
Oxides and Chalcogenides
Thin films of metal oxides and chalcogenides are versatile materials
used in anti-reflection coatings, transparent electrodes in solar
cells, gas sensors, varistors, surface acoustic wave devices,
and electro - and photoluminescent devices. An advantage of a
thin film material is that its properties can be modified to suit
the application. One major challenge being explored by centre
researchers is designing preparation procedures that are both
economical and flexible enough to provide thin films with varying
properties. One method, electrochemical deposition, has many advantages:
• it requires simple equipment
• t can be performed at or near room
temperature and atmospheric pressure
• it is easily scaled to cover large
areas
• altering deposition conditions
can yield films that are densely packed and smooth for optical
applications or that are open and very porous for use in sensors,
electrocatalysis, catalysis, and luminescence.
Zeolites
Guelph researchers are using hydrothermal syntheses to grow zeolite
thin films on conductive substrates. Formation of pin-hole free
films composed of nano-crystallites is important in developing
zeolite-modified electrodes which can act as sensors and templates
for nanostructure formation. Researchers are also using template-assisted
growth to form mesoporous films at conductive surfaces.
Porous Silicon Films
Rather than deposit material to form a thin film, resarchers may
selectively remove material to make porous films. For example,
a porous silicon film can easily be formed electrochemically,
with porosity tunable between 20% and 80%. While its most notable
property is it remarkable optical flourescence, centre researchers
are using such porous thin films to electrodeposit small nanostructures
of various metals and use the resulting synthetic structure as
an electrocatalyst whose electron transport properties are modified
by its unique structure.
Electrochemical OMCVD
A widely employed method for growing materials in the electronics
industry is organometallic chemical vapour deposition (OMCVD).
This process combines a particular metal atom with organic components
to dramatically increase its vapour pressure and increase its
reactivity. This precursor molecule then delivers the metal atom
to a substrate where it thermally deomposes to deposit the metal
directly or to present it for further reactions. Major problems
with this process include extreme sensitivity to contaminants
and toxicity of the airborne components. Centre researchers will
attempt to develop electrochemical methods to deposit these materials,
leveraging the electroreactivity of the precursors with techniques
being developed in nanotechnology.
|
