Fibrous structures on diamond and carbon surfaces formed by hydrogen plasma under direct-current bias and field electron-emission properties

Koji Kobashi, Takeshi Tachibana, Yoshihiro Yokota, Nobuyuki Kawakami, Kazushi Hayashi, Kazuhiro Yamamoto, Yoshinori Koga, Shuzo Fujiwara, Yasuhito Gotoh, Hironori Nakahara, Hiroshi Tsuji, Junzo Ishikawa, Franz A. Köck, Robert Nemanich

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Abstract

Polycrystalline diamond films, single crystal bulk diamonds, and diamond powder were treated in microwave plasma of hydrogen at 1.6 torr under a negative direct-current bias of -150 to -300 V without metal catalyst. It was found that fibrous structures, uniformly elongated along the direction normal to the specimen surface, were formed on the diamond surfaces. Similar experiments for glasslike carbon resulted in conical structures with frizzy fibers at the tops. Transmission electron microscopy measurements indicated that the fibers formed on diamond consisted of randomly oriented diamond nanocrystals with diameters of less than 10 nm, while the conical structures formed on glasslike carbon consisted of graphite nanocrystals. Field emission measurements of the fibrous specimens exhibited better emission efficiency than untreated ones. The field emission electron microscopy of the fibrous glasslike carbon showed a presence of discrete electron emission sites at a density of approximately 10,000 sites/cm2.

Original languageEnglish (US)
Pages (from-to)305-326
Number of pages22
JournalJournal of Materials Research
Volume18
Issue number2
Publication statusPublished - Feb 2003
Externally publishedYes

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ASJC Scopus subject areas

  • Materials Science(all)

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