Open AccessMechanism and enhancement of anti-parasitic-reaction catalytic activity of tungsten-carbide-coated graphite components for the growth of bulk GaN crystals
Author(s) -
Daisuke Nakamura,
K. Iida,
Kayo Horibuchi,
Yuko Aoki,
Naoko Takahashi,
Yuichi Mori,
Miki Moriyama,
Shugo Nitta,
Hiroshi Amano
Publication year - 2022
Publication title -
applied physics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.911
H-Index - 94
eISSN - 1882-0786
pISSN - 1882-0778
DOI - 10.35848/1882-0786/ac5ba4
Subject(s) - materials science , tungsten carbide , pyrolytic carbon , catalysis , annealing (glass) , graphite , chemical engineering , tungsten , inert , layer (electronics) , carbide , highly oriented pyrolytic graphite , epitaxy , metallurgy , composite material , chemistry , organic chemistry , pyrolysis , engineering
The working mechanism of the anti-parasitic-reaction (APR) catalyst of tungsten carbide (WC) coating on graphite in hydride vapor phase epitaxy GaN growth were examined. During NH 3 annealing, the surface of WC is reduced as well as nitrided. The W 2 N topmost layer was found to work as an APR-active catalyst to suppress the formation of GaN polycrystals during high-rate HVPE-GaN growth, while the regions covered with thick pyrolytic graphite residues were catalytically inert. The formation of an additional W 2 C top layer on the WC underlayer was demonstrated to exhibit superior APR activity, i.e. complete suppression of GaN polycrystal formation.