Formation of fibrous structures on diamond by hydrogen plasma treatment under DC bias

摘要

Diamond films and powders were treated in microwave plasma of hydrogen at 1.6 torr under a negative DC bias of 200 V for 3-6 h. As a result, a fibrous structure was formed on the diamond surface along the direction normal to the surface, while diamond was simultaneously etched at a rate of approximately 1 #mu#m/h. For a 3-h processing, the fiber diameter near the top end was <=50 nm and the fiber lengths were 2-3 #mu#m. Transmission electron microscopy (TEM) indicated that the fibers consisted of randomly oriented nanocrystals with diameters of <10 nm. The lattice spacings in the nanocrystals, obtained from TEM images, were 0.22 and 0.25 nm, and hence the structures were assigned to a strongly distorted diamond. An overgrowth of diamond on the fibrous structure resulted in an almost uniform coating of the fibers with crystal-faceted diamond.