Gas Adsorption Ellipsometer for Thin Film Characterisation

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One of the most important methods currently available for characterising the surfaceproperties of powders and porous materials is their ‘Brunauer–Emmett–Teller’ (BET) surfacearea which is determined using a gas adsorption isotherms, normally using nitrogen [1]. Suchisotherms also provide key information on the pore structure, surface chemistry andmorphology of powders. So utilitarian has become this laboratory technique that there areprobably worldwide over 50,000 of these BET instruments in daily laboratory operation.However, these systems cannot be used to study monolithic thin film samples. Thecharacterisation of such thin films is an area of increasing importance for semi-conductor,nano-porous films, graphene, catalysts and photo-voltaic materials to name but a fewimportant industrial applications. The ability to study the surface properties and structures ofthese classes of materials is key to both their development and their future commercialisation.This project will evaluate the technical feasibility of determining gas and vapour adsorptionisotherms on thin film substrates with surface areas of only a few square millimetres using anovel ellipsometric adsorption instrument. This instrument would allow a range of surfaceproperties of monolithic thin films to be determined for the first time routinely includingsurface area, surface energy, surface heterogeneity, surface diffusion, surface reactivity andsurface porosity. Such property measurements are key to the development of many classes ofnew nano-structured thin film materials.Such a successful development would offer the scope of commercialising AdsorptionEllipsometer as a major new research tool for the development of thin film materials.