Thin Films

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
  • it 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

Porous Silicon Films

Rather than deposit material to form a thin film, researchers 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 fluorescence, 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 decomposes 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.