Fabrication and properties of ultranano, nano, and microcrystalline diamond membranes and sheets

Thin diamond membranes and free-standin- sheets are of interest for a variety of potential applications. This article describes the film nucleation, microwave plasma-assisted chemical-vapor-deposition synthesis, and subsequent processing steps required to make free-standin- strong and flexible diamond foils of several cm(2). Films are initially deposited on silicon wafers as ultrananocyrstalline, nanocrystalline, or microcrystalline diamond by varying selected deposition parameters including gas composition. nucleation. power. substrate temperature, and pressure. Subsequently the diamond is separated from the original substrate and applied either to new substrates or to frames. Diamond membranes and sheets with thickness between I and 3 mum have been fabricated frorn each of these film types. The sheets are drapable and can be applied to curved surfaces and wrapped around cylinders. Properties of the films including optical transmission, Young's modulus and fracture strength are described. Several examples of foils and associated frames and substrates are given. (C) 2004 American Vacuum Society.