Oxygen '96
Early Stages of Oxygen Precipitation in Silicon
GENERATION OF THERMAL DONORS, NITROGEN-OXYGEN COMPLEXES AND
HYDROGEN-OXYGEN PAIRS IN Si
M. Suezawa
Institute for Material Research, Tohoku University, Sendai 980-77,
Japan
Keywords: thermal donor, oxygen, nitrogen, hydrogen, silicon, cluster
Clusters of impurities may be precursors of precipitation. Since the
number of constituent atoms included in clusters is essential for
determining the nature of clusters, the processes by which thermal
donors, nitrogen-oxygen complexes, and hydrogen-oxygen pairs are
generated were studied based on the measurement of optical absorption
associated with them after isothermal annealing of Si. The number of
constituent atoms can be determined by the analysis of the generation
process of clusters.
We measured optical absorption due to six
types of thermal donors, namely TD-1 through TD-6, generated due to
isothermal annealing of Czochralski-grown Si at 471 degrees C. We
analysed these data with a method which was extended from Kaiser
et al.'s treatment with chemical reaction equations. The number
of oxygen atoms included in TD-3 through TD-6 were determined to be 5
through 8 and those of TD-1 and TD-2 are proposed to be 3 and 4. The
activation energies for the generation of TD-1, TD-2 and TD-3 are 1.4,
1.7, and 2.1 eV, which are small compared to that (2.54 eV) of oxygen
migration.
We also studied the generation processes of
nitrogen-oxygen (N-O) complexes, which acted as shallow donors, from
the isothermal annealing of nitrogen-doped Czochralski-grown Si. We
analysed the processes by which those donors are generated with a
modification of Kaiser et al.'s method since there are two
kinds of constituent atoms, nitrogen and oxygen. The N-O-6 and N-O-3
complexes, the ground state energies of which are 36.21 and 37.02 meV,
are known to include 2 and 3 pairs of nitrogen atoms, respectively,
and one oxygen atom.
We found that a hydrogen atom made a pair
with an oxygen atom at around 50 degrees C. A peculiar characteristic
of this pair is that the vibrational frequency (1075.0 cm-1)
of a hydrogen-oxygen pair is smaller than that (1076.3
cm-1) of a deuterium-oxygen pair.
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Last modified: Mon Feb 19 17:21:20 GMT 1996
JG