Gas Adsorption Ellipsometer for Thin Film Characterisation

目前可用于表征粉末和多孔材料表面性质的最重要方法之一是其‘Brunauer-Emmett-Teller’(BET)表面积，该表面积是使用气体吸附等温线确定的，通常使用氮气[1]。这些等温线还提供了有关粉末的孔结构、表面化学和形貌的关键信息。这种实验室技术已经变得如此实用，以至于全世界可能有超过5万台这样的BET仪器在日常的实验室操作中。然而，这些系统不能用于研究单片薄膜样品。这类薄膜的特性对于半导体、纳米多孔薄膜、石墨烯、催化剂和光伏材料等几个重要的工业应用来说是一个日益重要的领域。研究这类材料的表面性质和结构的能力对它们的发展和未来的商业化都是关键。本项目将评估使用新型椭圆偏振吸附仪器在表面积仅为几平方毫米的薄膜衬底上测定气体和蒸汽吸附等温线的技术可行性。该仪器将允许首次常规地测定单片薄膜的一系列表面性质，包括表面积、表面能、表面非均质性、表面扩散、表面反应性和表面孔隙率。这种性能测量是开发多种新型纳米结构薄膜材料的关键。这种成功的开发将为吸附椭偏仪作为开发薄膜材料的主要新研究工具提供商业化的前景。

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.