Oxygen '96
Early Stages of Oxygen Precipitation in Silicon
THE NITROGEN-PAIR OXYGEN DEFECT IN SILICON
F. Berg Rasmussen(a), R. Jones (b), S. Öberg(c), C.
Ewels(b), J. Goss(b),
J. Miro(d), and P. Deák(d)
(a)Van der Waals-Zeeman Laboratorium, Universiteit van Amsterdam,
Valckenierstraat 65-67, NL-1018 XE Amsterdam, THE NETHERLANDS
(b)Department of Physics, University of Exeter, Exeter EX4~4QL, UK
(c)Department of Mathematics, University of Lule\aa ,Lule\aa, S95187,
SWEDEN
(d)Department of Atomic Physics, Technical University of
Budapest,
Budafoki út 8, H-1111 Budapest, HUNGARY.
Keywords: nitrogen, oxygen, infrared absorption, ab-inito theory.
The properties of nitrogen in silicon have attracted much
attention during the years. In oxygen-lean silicon the dominant
nitrogen defect is a nitrogen pair consisting of two neighbouring
<100> oriented N-Si split interstitials bonded into a squarelike
configuration lying on a {011} plane. Of special interest is the
interaction between the nitrogen pair and oxygen in oxygen-rich
material. Three infrared absorption lines at 1026, 996 and 801
cm-1, resp., were observed in N- and O-implanted FZ-Si
[1]. They were ascribed to a nitrogen-pair oxygen defect but no
microscopic model of the defect could be given. In this study we
combined measurements of the isotopic shift of the infrared absorption
lines with ab initio cluster calculations to deduce the
microscopic structure of the defect.
Infrared absorption
measurements have been carried out on FZ silicon samples implanted
with various combinations of 16O, 17O,
14N and 15N. The observed isotopic shifts are
consistent with a defect containing two nitrogen atoms and one oxygen
atom and show that the local modes of the three impurity atoms are
only weakly dynamically coupled.
Ab initio local density
functional cluster calculations were carried out on various models of
nitrogen-pair oxygen defects and the impurity-related vibrational
modes were evaluated in each case.
A model consisting of a
bridging oxygen atom adjacent to the nitrogen pair, accounts for the
dynamic properties of the observed defect with fair agreement between
measured and calculated isotopic shifts and is suggested as a model of
the defect.
[1]: H. J. Stein, in Oxygen, Carbon, Hydrogen and Nitrogen
in Crystalline Silicon, ed. J. C. Mikkelsen et al. (MRS,
Pittsburgh, PA, 1985) Vol. 59, p. 523
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Last modified: Sun Mar 17 15:09:59 GMT 1996
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