Mesoporous thin films are prepared using a simple sol–gel technique. Using lithographically patterned (100)‐orientated substrates and a dip‐coating method reproducible alignment of the pores across the substrate surface can be obtained. The pores preferentially align parallel to the long side of the channels etched into the surface. The channels within the aligned films are subsequently filled with cobalt (to form nanowire‐type structures) using a supercritical fluid inclusion technique, to allow high‐resolution imaging of the pore by using secondary electron microscopy. The channel structure imposes a strain on the mesoporous arrangement resulting in some variation in d‐spacings compared to simple films. The results indicate that the topographic structure can be used to engineer the placement and directionality of the pore structure and the potential of the aligned mesostructures are discussed.

Clear and homogeneous precursors for casting mesoporous thin films (MTFs) were prepared by addition of a triblock polyalkylene oxide amphiphilic surfactant (the structural directing agent) to a clear sol of tetraethylorthosilicate. Films were developed by dip-and spin-coating methods and calcined to yield high quality crack-free coatings containing highly ordered hexagonal arrangements of mesopores. Comparison of the dip-coating and spin-coating methods was made using X-ray methods including powder X-ray diffraction, reciprocal space mapping, X-ray reflectometry and in-plane scattering. In all cases, the films had a highly textured nature with preferential alignment of pores parallel to the substrate. It was found that the dip-coating method resulted in better quality films with greater long range order. The varied X-ray methods provided a detailed structural analysis of the mesoporous thin films which showed a distorted hexagonal arrangement. The results defining pore size could be directly and favourably compared to TEM and N 2 isotherm data. It was found that all the techniques are in reasonable agreement.

In this work we report how single crystal nanowires can be assembled into regular arrays using mesoporous thin films to define the architecture. Mesoporous thin films were prepared by a sol-gel method. These provide films of very regular structure and dimensions. The films produced in this way have almost single crystal like structures and can also exhibit strong epitaxy to the underlying silicon substrate. The films are subjected to a supercritical fluid (SCF) environment in which a precursor is decomposed to yield nanowires of metals, semiconductors or oxides. Using these SCF conditions, pore filling is complete and the products are nanowires which are single crystals and structurally aligned in one direction. The growth mechanism of the nanowires is described and size effects discussed.

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