Surfactant-assisted fabrication of free-standing inorganic sheets covering an array of micrometre-sized holes

Thin inorganic membranes are of importance to a number of applications such as sensing, catalysis and separation. Here, we present a method to fabricate free-standing sheets of various inorganic materials such as C, Si, Pt, Fe and CdSe with thicknesses ranging from a few to a hundred nanometres. First, an array of holes in a flat substrate was uniformly covered by dried-foam-film (DFF) self-standing reversed bilayers of surfactants. As the surfactant bilayers are sufficiently robust to allow deposition of amorphous films, a variety of inorganic films were then fabricated on the DFFs using physical deposition techniques such as sputtering, electron-beam deposition and thermal deposition. The films thus obtained showed improved thermal stability compared with the DFFs. This fabrication method therefore provides a flexible and reliable way to readily produce free-standing inorganic multilayered structures.