Study of ion-implanted and post-annealed CVD diamond by TEM

A novel method has been employed for ex situ study of ion-implanted and post-annealed polycrystalline diamond by transmission electron microscopy (TEM) without reduction of specimen thickness, Chemical-vapor-deposited (CVD) diamond used for TEM study was directly deposited onto Mo TEM grids, and then implanted and post annealed. TEM images clearly revealed the existence of an ion-induced amorphous layer on the as-implanted CVD diamond surface, in which some graphite-like structures were embedded. The amorphization processes depended on the irradiation conditions. Hydrogen plasma treatment was used to anneal the as-implanted CVD diamond. High-resolution electron microscopy (HREM) images showed that hydrogen plasma treatment can effectively remove the ion-induced surface amorphous layer without diamond graphitization. After the treatment, high-density ball-like diamond blisters appeared on the surface, the average diameter of which was only about 2.5 nm, implying that the critical size for the stable existence of CVD diamond crystallites might be on the order of a few atomic layers.