Nucleation effects and characteristics of diamond film grown by arc discharge plasma jet chemical vapor deposition

Abstract

In this report, we discuss nucleation effects, and characteristics of diamond film synthesized by arc discharge plasma jet chemical vapor deposition in a methane atmosphere with a high growth rate. To observe the internal structure of the diamond film, we cut the diamond film with a YAG laser, polished the cut surface with a diamond film polishing apparatus using a hot metal plate, then observed and analyzed the polished surface. The structure of the diamond film is different between the {100} and {111} sectors; the {100} sector is clear except for marks of step growth, whereas the {111} sector consists of numerous flaky crystallites. The surface ratio of the {100} sector is similar to that of the {111} sector, when the thickness is within 50 μm; however, the proportion of {100} sector increases with increasing distance from the substrate. The crystallinity of the {100} sector is better than that of the {111} sector. The contamination of hydrogen in the {111} growth sector is twice as large as that in the {100} sector. In addition, the effects of surface treatment of the substrate and methane concentration on the surface unevenness and porosity were investigated. Diamond film with small surface unevenness and no porosity is fabricated under fluctuating methane concentrations in the range 3.5%–7%.