Deposition Behavior of Boron-Doped Diamond with Varying Amount of Acetone by Hot Filament Chemical Vapor Deposition

As a carbon source for hot filament chemical vapor deposition of boron-doped diamond (BDD), cost-effective acetone (C 3 H 6 O) was used instead of commonly used methane gas. In this case, tantalum filaments turned out to be more suitable than tungsten filaments because tantalum is more oxidation-resistant and can be heated to much higher temperature without evaporation than tungsten. As the acetone flux was varied, the hydrogen flux was also varied so that the mixture of acetone and hydrogen fluxes was fixed at 500 standard cubic centimeter per minute (sccm). Trimethyl borate (TMB) was used as a boron source. As the acetone flux was varied, the TMB flux was also varied so that the boron doping of 11,400 ppm was maintained. As the flux of acetone was increased from 90 to 170 sccm, the grain size and the film thickness of BDD increased. In this range of acetone fluxes, the films showed well-defined (111) facets, indicating that the high quality diamond was deposited. When the acetone flux was increased to 210 sccm, the grain size decreased abruptly and the film thickness, which represents the deposition rate, decreased also. When the acetone flux was increased to 250 sccm, the grain size further decreased, producing a cauliflower structure and the film thickness further decreased. The potential window, which is measured as electrochemical properties of BDD, increased as the acetone flux increased from 90 to 170 sccm and did not change much between 170 and 250 sccm. From this experiment, it was confirmed that varying the flux of acetone could control the morphology, the growth rate and the electrochemical properties of the BDD film. Graphical Abstract