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Cz-grown, carbon-doped silicon samples were irradiated by fast neutrons. We investigated the annealing behaviour of oxygen-related defects, by infrared spectroscopy. We studied the reaction channels leading to the formation of various VmOn defects and in particular the VOn defects formed by the accumulation of oxygen atoms and vacancies in the initially produced by the irradiation VO defects, as the annealing temperature ramps upwards. We mainly focused on bands appearing in the spectra above 450 oC. A band at 1005 cm-1 is found to be the convolution of two bands at 1004 and 1009 cm-1. The latter band has the same thermal stability with the 983 cm-1 of the VO4 defect and therefore is also attributed to this defect. The former band has the same thermal stability with three other bands at 965, 1034 and 1048 cm-1. These four bands may be attributed to VOn (n=5,6) defects, although other VmOn complexes are also potential candidates. Furthermore, we found that pre-treatments of the samples at 1000 oC, with or without the application of high hydrostatic pressure lead to an increase in the concentration of the VO2, VO3 and generally VOn defects in comparison with that of the untreated samples.

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Complementary infrared and transmission electron microscopy studies of the effect of high temperature-high pressure treatments on oxygen-related defects in irradiated silicon Hydrogen-defect complexes formed by neutron irradiation of hydrogenated silicon observed by optical absorption measurement Infrared spectroscopy was used to study the defect spectrum of Cz-Si samples following fast neutron irradiation. We mainly focus on the band at 533 cm À1 , which disappears from the spectra at $170 C, exhibiting similar thermal stability with the Si-P6 electron paramagnetic resonance (EPR) spectrum previously correlated with the di-interstitial defect. The suggested structural model of this defect comprises of two self-interstitial atoms located symmetrically around a lattice site Si atom. The band anneals out following a first-order kinetics with an activation energy of 0.88 6 0.3 eV. This value does not deviate considerably from previously quoted experimental and theoretical values for the di-interstitial defect. The present results indicate that the 533 cm À1 IR band originates from the same structure as that of the Si-P6 EPR spectrum. V C 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4831963] FIG. 3. Arrhenius plot for the decay of the 533 cm À1 band for the S 1 (a), the S 2 (b), and the S 3 (c) samples.

Thermal treatments of Czochralski-grown Si at T = 450, 600 and 650 • C, under high hydrostatic pressure of P ≈ 11 kbar, introduce thermal donors and various structural defects, as for example oxygen precipitates. Neutron irradiation of such samples results first in the formation of oxygen-vacancy complexes, mostly VO defects. Upon annealing, the VO defects evolve in larger clusters via the accumulation of oxygen atoms and vacancies in the initial VO core, leading to the formation of V m O n defects. We focus on the study of the effect of pre-treatments on the production and evolution of the various V m O n defects upon isochronal annealing. The observed changes and variations in the IR spectra and the evolution curves in comparison with the corresponding ones of an initially untreated sample are discussed and some explanations are offered. The most important finding of this work is that the concentrations of the VO 2 and the VO 3 defects are reduced in the sample pre-treated at 450 • C, an indication of interaction between thermal donors and radiation-induced defects.