Unveiling the magic of H 2S on the CVD-Al 2O 3 coating

Takatoshi Oshika, Akio Nishiyama, Yoshifumi Ito, Kouichi Nakaso, Manabu Shimada

Research output: Contribution to journalArticlepeer-review


Achieving a uniform film thickness profile over a substrate has been difficult in CVD-Al 2O 3 coating processes. Although this problem can be solved by H 2S-doping to the source gas mixture, AlCl 3/CO 2/H 2, the role of H 2S in the mechanisms of the CVD coating have not been clarified. In this study, the effects of H 2S-doping on the improvement of the uniformity of a coated layer is studied, focusing on the particles generated in the gas phase. It is found in the measurement of gasborne particles that the number concentration of particles larger than 200 nm in diameter is reduced dramatically by the H 2S-doping. The concentration is over 10 8 particles/m 3 when no H 2S is doped, while it is less than 10 6 particles/m 3 at 0.20% doping. The improvement of the coating by H 2S-doping is concluded to be caused by a size reduction of particulate matters of the Al 2O 3 precursors that leads to an increase of the diffusivity.

Original languageEnglish
Pages (from-to)752-753
Number of pages2
JournalKagaku Kogaku Ronbunshu
Issue number6
Publication statusPublished - 2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Materials Science (miscellaneous)


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