Scanning tunneling microscopy measurements of the initial erosion of graphite by hyperthermal atomic oxygen and neon

Matlis, Sophie; Vered, R.; Lempert, G.; Marom, G.; Lifshitz, Y.

doi:10.1016/0266-3538(93)90147-9

Cited by 7 publications

(3 citation statements)

References 9 publications

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“…The surface properties of carbon materials and their modification are highly relevant in many applications. These include first-wall materials for nuclear reactors, − re-entry shields of spacecraft, biomedical materials, − anodes for fuel cells , and Li-ion batteries, or catalyst supports. , Among the existing methods for the surface modification of carbon materials (e.g., bombardment with high and low , energy ions, high temperature oxidation, or wet chemical and electrochemical oxidation), surface modification by plasmas is particularly attractive owing to a number of advantageous features: it is a nonpolluting, potentially scalable process, the modification is strictly restricted to the surface of the material without affecting its bulk properties, the treatments are relatively easy to control, and different chemical species can be readily obtained just by changing a few processing parameters . In particular, plasma oxidation (i.e., plasma treatment under oxygen-containing gases) is widely employed to control such properties as adhesion, molecular adsorption, wettabilitty, or surface porosity. − …”

Section: Introductionmentioning

confidence: 99%

A Combined Experimental and Theoretical Investigation of Atomic-Scale Defects Produced on Graphite Surfaces by Dielectric Barrier Discharge Plasma Treatment

et al. 2009

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The characteristics and nature of atomic-scale defects produced on graphite surfaces by dielectric barrier discharge (DBD) plasma oxidation have been investigated, both experimentally and theoretically. Two main types of defect visualized by scanning tunneling microscopy (STM) were studied: protrusions ∼1-5 nm in diameter and smooth circular depressions 5-7 nm wide, the latter constituting a novel type of defect on carbon surfaces that was only very recently reported for the first time. STM and atomic force microscopy (AFM) experiments indicated that both the protrusions and the depressions are not associated to topographical features on the graphite surface and that their observation by STM should be related to electronic effects. The thermal behavior of the protrusions, which could only be removed at a temperature of ∼900 °C, as well as their reactivity toward molecular oxygen, allowed their identification as multiatomic vacancies. In comparison, the depressions displayed a higher thermal stability (they could be eliminated only at ∼1200 °C) and a lower reactivity toward oxidation. Density functional theory (DFT) calculations suggested that the depressions are associated with two-dimensional clusters of interstitial oxygen formed by the agglomeration of migrating oxygen atoms. Such clusters induce a lowering in the local density of electronic states on the graphite surface and are therefore detected as a depression by STM. Taken as a whole, the findings reported here provide a consistent picture of the basic mechanism underlying the modification of graphitic surfaces by this type of plasma, which is driven by physical processes (i.e., ion bombardment).

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Section: Introductionmentioning

confidence: 99%

A Combined Experimental and Theoretical Investigation of Atomic-Scale Defects Produced on Graphite Surfaces by Dielectric Barrier Discharge Plasma Treatment

et al. 2009

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“…[2][3][4][5] It was shown that the erosion rate depends drastically on the crystalline structure and the sp 2 / sp 3 ratio. Several studies on the interaction of diamond with atomic oxygen ͑AO͒, which is the main constituent of space environment at low earth orbit ͑LEO͒, 1 showed its high stability compared to other forms of carbon-based materials.…”

Section: Introductionmentioning

confidence: 99%

“…Several studies on the interaction of diamond with atomic oxygen ͑AO͒, which is the main constituent of space environment at low earth orbit ͑LEO͒, 1 showed its high stability compared to other forms of carbon-based materials. [2][3][4][5] The quantity that shows the susceptibility of a material to atomic oxygen is the erosion yield, which is defined as the volume of material lost per incident oxygen atom. 5 Carbon in the form of highly oriented pyrolitic graphite, amorphous hydrogenated carbon ͑a :C:H͒, and diamondlike carbon demonstrates high erosion rate.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of diamond films by atomic oxygen: High resolution electron energy loss spectroscopy studies

Shpilman

Gouzman²,

Grossman³

et al. 2007

Journal of Applied Physics

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Investigation of oxygen-related defects and the electrical properties of atomic layer deposited HfO 2 films using electron energy-loss spectroscopy High resolution electron energy loss spectroscopy study of Fomblin Z-tetraol thin filmsa) A combined scanning tunneling microscopy and electron energy loss spectroscopy study on the formation of thin, well-ordered β-Ga 2 O 3 films on CoGa (001) Diamond surface oxidation by atomic oxygen, annealing up to ϳ700°C, and in situ exposure to thermally activated hydrogen were studied by high resolution electron energy loss spectroscopy ͑HREELS͒. After atomic oxygen ͑AO͒ exposure, HREELS revealed peaks associated with CH x groups, carbonyl, ether, and peroxide-type species and strong quenching of the diamond optical phonon and its overtones. Upon annealing of the oxidized surfaces, the diamond optical phonon overtones at 300 and 450 meV emerge and carbonyl and peroxide species gradually desorb. The diamond surface was not completely regenerated after annealing to ϳ700°C and in situ exposure to thermally activated hydrogen, probably due to the irreversible deterioration of the surface by AO.

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Chemical and morphological aspects of diamond film oxidation and regeneration

Shpilman

Gouzman²,

Grossman³

et al. 2008

Physica Status Solidi (a)

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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)

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Scanning tunneling microscopy measurements of the initial erosion of graphite by hyperthermal atomic oxygen and neon

Cited by 7 publications

References 9 publications

A Combined Experimental and Theoretical Investigation of Atomic-Scale Defects Produced on Graphite Surfaces by Dielectric Barrier Discharge Plasma Treatment

A Combined Experimental and Theoretical Investigation of Atomic-Scale Defects Produced on Graphite Surfaces by Dielectric Barrier Discharge Plasma Treatment

Oxidation of diamond films by atomic oxygen: High resolution electron energy loss spectroscopy studies

Chemical and morphological aspects of diamond film oxidation and regeneration

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