NUCLEATION OF DIAMOND DURING HOT FILAMENT CHEMICAL VAPOR-DEPOSITION

We have investigated the mechanism of nucleation of diamond during hot filament chemical vapor deposition process by high resolution transmission electron microscopy. Diamond was deposited on copper grids which were directly mounted on a high resolution transmission electron microscopy holder in order to study nucleation and growth characteristics of crystalline diamond. We have found direct evidence for the formation of a diamond-like amorphous carbon layer 8-14 nm thick in which small diamond microcrystallites about 2-5 nm across were embedded. These diamond microcrystallites were formed as a result of direct transformation of diamond-like carbon into diamond. Large diamond crystallites were observed to grow from these microcrystallites. It is envisaged that the diamond microcrystallites present in the amorphous diamond-like carbon layer provided nucleation sites for diamond growth on which the large diamond crystallites grew.