Oxygen '96
Early Stages of Oxygen Precipitation in Silicon
INJECTION ENHANCED REACTIONS OF INTERSTITIAL DEFECTS IN
SILICON
B. N. Mukashev,
Kh. A. Abdullin and
Yu. V. Gorelkinskii
Physical Technical Institute, National Academy of Sciences, 480082,
Almaty, Kazakstan
Keywords: defect, silicon, irradiation, selfinterstitial, injection
In this paper we report experimental evidence of strong
ionisation effect on the self-interstitials formation and its
stability in silicon.
DLTS and TSCAP studies of pulled (CG) and floating-zone-grown (FZ)
silicon doped boron or aluminium (=0.2-1 Ohm/cm2) are
performed. Samples are irradiated by electrons, protons or
alpha-particles at 77 K. Spectra of all proton- and alpha-irradiated
samples are revealed E1=Ec-0.39 eV defect state. This is
the main defect in these samples in contrast to electron irradiated
silicon. It is important to note that E1 defect is stable up to
320-350 K, however under injection conditions it is annealed out at 77
K. The annealing of E1 centres is accompanied by appearance of
Ci centres (H1=Ev+0.29 eV), Ali
centres in Si(Al)-FZ and additional H2=Ev+0.13 eV level in
CG samples. E1-defect was identified as a selfinterstitial centre
[1]. The reversible transition between E1 and H2 defects is occurred:
E1 annealing under injection at 77 K increases the concentration of H2
centre and the annealing at 180-200 K transforms H2 into E1. It is
supposed that H2 defect belongs to (Sii -Oi)
complex therefore the reaction Sii+Oi H2
(Sii -Oi ) explains observed reversible
transformation. This result demonstrates that E1 defect migrates at 77
K under injection condition without decomposition.
ESR studies of the CG and FZ samples irradiated at ~80 K were resolved
new high intensive spectrum (labelled Si-AA12) with isotropic g=1.9998
(77 K) and 29Si hyperfine (hf) interaction (~45.5 MHz) from
one silicon atom. It is also observed unresolved hf interaction (~9.5
MHz) from four equivalent silicon atoms. This centre is detected in
FZ immediately after irradiation and in CG silicon after annealing at
180-250 K . The correlation between behaviour of this centre and
E1-defect is found: i) both centres are emptied at 140-160 K (but
subsequent light illumination is recovered of the line amplitude), ii)
thermal annealing is occurred at 320-350 K, iii) ESR signal of
Ali (G18) is appeared after annealing of the AA12 (it is
known that G18 was observed in silicon after electron irradiation at 4
K [2]). Tentative model of defect responsible after annealing of the
AA12 (It is known that G18 was observed in silicon after electron
irradiation at 4 K [2]). Tentative model of defect responsible for the
E1-level and AA12 ESR centre are proposed. Effects of ionisation and
elastic stopping power of protons, alpha-particles and electrons on the
interstitial formation and stabilisation are discussed.
[1] Kh.A.Abdullin, B.N.Mukashev, M.F.Tamendarov
and T.B. Tashenov, Phys. Lett. A, 144 (1990), p. 198, ibid, 166 (1992)
p. 40.
[2] G.D.Watkins, Radiation Damage in Semiconductors
(1964), p. 97.
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