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Surface chemical effects of low‐energy N 2 + ion bombardment on single crystalline α‐Al 2 O 3
Author(s) -
Espinós J. P.,
GonzálezElipe A. R.,
Mohai M.,
Bertóti I.
Publication year - 2000
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/1096-9918(200008)30:1<90::aid-sia796>3.0.co;2-q
Subject(s) - nitrogen , x ray photoelectron spectroscopy , nitride , oxygen , metal , chemistry , oxide , ion , analytical chemistry (journal) , stoichiometry , inorganic chemistry , chemical engineering , organic chemistry , layer (electronics) , chromatography , engineering
Composition changes and chemical structure alterations initiated by ion beams on metal oxide surfaces have been widely studied. Significant differences in the effect of low‐keV inert (Ar + ) and reactive (N 2 + ) ion impact on a series of metal oxides have been published recently by the present authors. In this work the effect of 0.5–5 keV N 2 + bombardment on single crystalline α‐Al 2 O 3 was studied by quantitative XPS. Clarifying the existing ambiguity, experimental evidence is presented that supports the preferential oxygen loss and build‐up of nitrogen. The oxygen loss increased with increasing N 2 + ion energy until approaching an atomic ratio saturation value of O/Al ∼1 on 3.5 keV bombardment with the concomitant build‐up of N at N/Al ∼0.5. In contrast to other oxides, for α‐Al 2 O 3 two major types of nitrogen were detected on N 2 + impact; the two N 1s lines were separated by 7 eV. The one at 396.4 eV binding energy corresponds to a nitride‐type N–Al environment, similar to that found in bulk AlN. Formation of the nitride is interpreted as the result of replacement of lattice oxygen around Al by implanted nitrogen in a two‐stage process. The 403.4 eV component is assigned to nitrogen trapped in the cation‐deficient lattice of α‐Al 2 O 3 in empty octahedral sites surrounded by oxygen atoms bonded to Al. Both of these chemical states of nitrogen were stable on heating up to 550–650 °C. Copyright © 2000 John Wiley & Sons, Ltd.