Oxygen '96
Early Stages of Oxygen Precipitation in Silicon
COMPLEXES OF OXYGEN AND GROUP II IMPURITIES IN SILICON
E. McGlynn (a),M. O. Henry (a), S. E. Daly (a) and
K. G.McGuigan (b)
(a) School of Physics Sciences, Dublin City University, Collins
Avenue, Dublin 9, IRELAND.
(b) Department of Physics, Royal College of Surgeons, St. Stephens
Green, Dublin 2, IRELAND.
Keywords: oxygen, silicon, photoluminescence, group II
A comprehensive photoluminescence (PL) study of both oxygen-rich (CZ)
and oxygen-lean (FZ) silicon samples implanted with the group II
impurities Be, Zn and Cd shows that oxygen-rich material annealed in
the range 450-600 degrees C contains defects not observed in
oxygen-lean samples. For Be, one defect dominates the PL spectrum
(~1138 meV). In the case of Zn a series of PL lines is observed with
relative intensities which are dependent on the annealing treatment
(1130, 1100, 1090 and 1050 meV). For Cd, the PL spectrum contains
three Cd-related line systems whose relative intensities are also
dependent on the annealing treatment (1025, 982 and 935 meV).
Uniaxial stress measurements show that all of these defects are of
rhombic I or monoclinic I symmetry, and the stress fitting parameters
vary little between the defects. Temperature dependence measurements
likewise show broadly similar behaviour and in every case the
zero-phonon lines are found to be magnetic singlets.
Isotope
substitution experiments, in the case of Zn and Cd, have confirmed the
involvements of these elements, and experiments using co-implantation
of oxygen isotopes into FZ samples have also been conclusive regarding
the involvement of oxygen except for Si:Cd samples.
The weight of
the evidence is that the high concentration of oxygen in the CZ
material is the determining factor for the creation of these
defects. We conclude that this group of defects results from the
complexing of oxygen atoms with the implanted group II element. The
indications from Zeeman and uniaxial stress measurements are that in
each case the PL originates from the recombination of a loosely-bound
electron with a hole localised at the defect core.
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Last modified: Mon Feb 19 12:11:09 GMT 1996
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