Layered Functional Ceramics via Misted Chemical Solution Deposition

A review is given of "misted" CSD deposition. This technique uses stoichiometrically correct sol-gel solutions but is not a spin-on process. Instead a monodisperse mist of droplets as large as 3 microns in diameter or as small as 0.3 microns is deposited on a substrate. This technique has the great advantage over sol-gel spin-on processing in that it is suitable for nonplanar structures, including nanotubes and nano-wires. One could coat a variety of objects with this technique, including anything from non-planar flash-goggles to a parabolic mirror or focal-plane array of pyroelectric detectors. Yet it is much simpler and less expensive than conventional chemical vapour deposition (CVD). We illustrate its use with functionally graded layers on platinised silicon wafers, on nanotubes of piezoelectrics, and most recently [Pollard, Gregg, et al.] on 100 Gbit/cm2 arrays of Pt nanowires on Si substrates (the latter are 30-nm diameter, spaced 50 nm apart, embedded in porous alumina and capped with lead zirconate titanate capacitors).