Premium
Chemical and morphological aspects of diamond film oxidation and regeneration
Author(s) -
Shpilman Z.,
Gouzman I.,
Grossman E.,
Akhvlediani R.,
Hoffman A.
Publication year - 2008
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200879708
Subject(s) - diamond , hydrogen , chemical vapor deposition , oxygen , annealing (glass) , chemical engineering , chemistry , surface layer , materials science , analytical chemistry (journal) , nanotechnology , layer (electronics) , composite material , environmental chemistry , organic chemistry , engineering
Hot Filament – CVD diamond films with sub‐micron grain size have been exposed to atomic oxygen (AO) and annealed in ultra‐high vacuum at 700 °C. After oxidation, the surface was exposed in‐situ to thermally activated hydrogen or ex‐situ to hydrogen MW plasma in order to assess the surface regeneration mechanism. The morphological effects of hydrogen plasma were compared to the effects of oxygen plasma exposure. High Resolution Electron Energy Loss Spectroscopy (HREELS) was used to evaluate the surface bonding states, while tapping mode Atomic Force Microscopy (AFM) measurements were used to visualize surface morphology and to identify the preferential etching sites. Atomic oxygen exposure results in a very low erosion yield of the CVD diamond films, but significantly affects chemical composition of the upper surface layer. The main constituents of the surface after exposure to AO are saturated and unsaturated hydrocarbon species and oxygen‐bonded fragments. The diamond optical phonon (OP) overtones are absent indicating on a non‐diamond top layer. Gradual annealing and exposure to thermally activated hydrogen leads to a removal of hydrocarbons and oxygen containing species, and emergence of the diamond OP overtones. However, regeneration of diamond surface was not complete. On the other hand, the MW‐hydrogen treatment of the AO exposed sample fully regenerates chemical composition of diamond surface. Changes of the diamond surface morphology after exposure to AO are mild. The thermally activated hydrogen does not affect the surface morphology, while hydrogen MW plasma treatment severely damages the surface, resulting in selective etching of certain diamond facets. Oxygen plasma also leads to severe morphological damage, but in this case the damage was uniform, creating a dense granular phase on top of the diamond film. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)