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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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Last modified: Wed Feb 28 09:49:20 GMT 1996 JG
                                                                                                                                                                                                                                                                       

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