High optical transparency and good adhesion of diamond films deposited on fused silica windows with a surface-wave sustained plasma.

We utilized a microwave plasma reactor based on a surface-wave-sustained discharge for uniform coating of fused silica windows with polycrystalline diamond films. Grain size and average roughness as small as 30 and 2.2 nm, respectively, were obtained, resulting in a uniform loss of transparency of only 10% over the 190-800-nm band for as-deposited 1.5-mum-thick coatings. A pretreatment procedure provides a film coating with a surface resistance to scratching that is approximately a factor of 2 higher than that of bare fused silica.