Nature and parameters of radiation defects in epitaxial layers of silicon

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Abstract
The peculiarities of the radiation defects accumulation processes during irradiation by60Co γ-quanta and rearrangement of these defects at further isochronal annealing are studied for n-type silicon epitaxial layers of 1.2 and 5 μm thickness and ρ = lΩ.cm. The experimental results are based an analysis of the Hall coefficient temperature dependencies obtained at various stages of irradiation or annealing. It is established that, as compared to bulk crystals, the epitaxial silicon layers demonstrate a number of salient features during radiation defect formation and annealing. Among them are the lower rate of vacancy defects introduction, lower annealing temperature for certain defects etc. It is demonstrated that these features are caused by interaction of irradiation-generated mobile-at-annealing defects with the surface and atoms of impurities. The vacancies generated by γ-quanta efficiently migrate to the surface. This process decreases the rate of vacancy defects formation in thin layers. The layers are characterized by non-uniform profile of technological impurities such as oxygen and carbon which capture irradiation-generated Frenkel pairs with formation of electrically active defect complexes (Ci;Cs, A-centers); a gradient in the distribution of the complexes is thus created. TheCiCs complexes are mainly formed near the surface and theA-centers are created near thep-n layer-substrate junction.