Bias-induced structural evolution of diamond films in plasma enhanced hot filament chemical vapour deposition with a two-step process

We report the structural evolution of diamond films in a plasma assisted hot filament chemical vapour deposition system with a variable substrate bias through a two-step process including deposition and subsequent modification. It is found that the diamond surfaces can be significantly modified after the treatment of hydrogen plasma. The surfaces with pyramidic structures form under the proper treated duration and temperature with a decrease in the content of amorphous carbon. As the treatment is prolonged, the surface presents ellipsoid structures while the diamond film becomes amorphous. Furthermore, 50 µm-long columns appear instead of the ellipsoids in a higher regime of the substrate temperature. These results suggest that the hydrogen plasma treatment and substrate temperature can significantly tune the surface topography of diamond films, and even give rise to chemical bonding variations with pronounced surface structures.