Accumulation of defects in silicon at superhigh doses of electron irradiation

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Abstract
An apparent charge of local vibration due to the vacancy-oxygen complex (absorption bands 835 and 884 cm−1) was determined on the basis of joint measurements of IR-absorption, EPR and the temperature dependencies of the Hall effect on 1 and 3.5 MeV electrons irradiated n-type silicon samples. The value obtained enables us to apply the IR-absorption method to determine the absolute values of the concentration of vacancy-oxygen complexes in silicon at superhigh irradiation doses (∼ 1018 - 1020 cm−2) under the conditions when their concentration was near to the limiting one. The IR measurements showed that within the above dose range the complex concentration varies slightly and is ∼4.1017 cm−3, with the concentration of the interstitial oxygen uncombined in complexes remaining rather high (∼4.1017 cm−3) even at the dose of ∼1, 16.1020 cm−2. An analysis causing saturation of the A-centres concentrations with the dose in the presence of a large amount of free interstitial oxygen has been done in the work. The question of the limiting change of the semiconductor crystal parameters resulting from electron irradiation is discussed.