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The processes of radiation defect formation and annealing in dislocation-free n-type Si (ϱ = 100 Ω cm) grown by the float-zone technique in argon atmosphere or in vacuum are studied. In the latter case the ingot is grown at a varying rate and therefore contains A-, A + B-, and D-type microdefects in different parts. Crystals obtained in argon atmosphere do not involve microdefects identified by selective etching. The temperature dependences of the charge carrier lifetime (τ) and the Hall coefficient (RH) are measured. The variation in τ and RH after 60Co γ-ray irradiation at T = 330 K is found to be due to the accumulation of E-centres with the level Ec −0.43 eV. However, the E-centre introduction efficiency and annealing temperature in Si grown in argon atmosphere as well as in crystals with A + B-type microdefects are lower than in control Si with small content of dislocations (ND = 1 × 104 cm−2) where microdefects are absent. It is concluded that under certain growing conditions (gaseous atmosphere, growth rate, axial temperature gradient) of dislocation-free crystals, shallow (according to the estimates of 10 to 20 atoms) interstitial-type inclusions unidentified by selective etching can be formed in their bulk which produce strain fields around themselves and thereby are surrounded by an impurity atmosphere. Affected by the strain fields induced by inclusions, primary radiation defects migrate directedly towards them whereby accumulation of secondary complexes occurs around inclusions within the impurity atmosphere. For the same reason the E-centre formation efficiency in crystal matrix decreases and their annealing parameters change due to the effect to strain fields. Inclusions are assumed to be predecessors (fragments) of B- or D-type microdefects. [Russian Text Ignored].

Radiation-defect accumulation and annealing have been examined for nucleardoped silicon in relation to germanium doping level. Results have been obtained from the temperature dependence of the Hall coefficient at various stages in60Co gamma irradiation and subsequent annealing. The formation rates for the main compensating defects (other than A centers) vary nonmonotonically, while the annealing temperatures for carbon-bearing complexes containing E1 levels increase with the germanium concentration. The results are interpreted on the assumption that there are dopant-defect inclusions whose gettering behavior and surrounding stresses are dependent on the germanium level. It is also concluded that there are changes in the effective free-vacancy and interstitial carbon-atom trapping cross sections for oxygen in the presence of germanium.

The variation in the nonequilibrium charge-carrier lifetime (τ) is studied under irradiation with 60Co γ-rays (Tirr ⪅ 50 °C) and subsequent isochronal annealing (Tann = 100 to 650 °C) of zone floated and pulled n-Si (ϱ ≈ 100 Ω cm) containing higher densities of dislocations introduced at plastic deformation (ND = 1 × 102 to 1 × 107 cm−2). τ is measured (Tmeas = 300 K) by the method of conductivity modulation at a point contact at different nonequilibrium charge-carrier injection levels. The regularities established of the τ-variation and its dependence on radiation-thermal treatments of the crystals studied are explained taking into account the interaction of radiation defects and their components, mobile under the experimental conditions, with dislocations. As a result, both the structure of the dislocations and thereby their recombination activity change. The presence of an impuritiy atmosphere near the dislocations is shown to prevent the rearrangement of the dislocation structure under irradiation but to facilitate it at annealing. [Russian Text Ignored.]

The formation of donor-type defects (T = 300 to 400 °c) is observed when annealing 60CO γ-ray irradiated dislocation-free float-zone n-Si (ϱ = 100 Ω cm). It is assumed that in the bulk of such crystals inclusions of interstitial type are present which produce anisotropic strain fields and as a result are surrounded by an atmosphere of back ground impurities within which irradiation-induced accumulation of A-centres and interstitial carbon–substitutional carbon complexes (level ≈ Ec — 0.18 eV) occurs. When annealed these defects interact with each other with the result that electrically inactive carbon–poxygen associates are formed which participate in the formation of donor centres whose properties resemble those of thermal donors I. [Russian Text Ignored.]

The temperature and injection dependence of the charge-carrier lifetime in dislocation-free n-Si is analyzed, making it possible to characterize the recombination activity of various types of microdefects. The parameters of the primary recombination centers with A-and B-type microdefects have been found.

The production of radiation defects in float-zone and pulled n-Si (ϱ = 1 to 500 Ωcm) irradiated by protons with energy 16,30,660, and 8600 MeV at T ≦ 320 K is studied. The changes in the initial rates of charge-carrier concentration and Hall mobility decrease under irradiation as a function of residual (technological) and doping impurity content are analysed. It is concluded that the impurity content has weak influence on radiation defect production processes under this irradiation. It is due to the fact that irradiation-induced defects are localized preferentially in clusters which consist of the core and the impurity-defect shell. Defect clustering leads to a shift of the ionization temperature range. This effect is used for estimating the size of the cluster core and the impurity-defect shell. It is shown that the sizes of the shell are, for the most part, dependent on the concentration of impurities contained in the crystal, while the core sizes are determined by the proton energy. [Russian Text Ignored].

Radiation defect accumulation in 60Co γ-ray-irradiated n-type Si single crystals (ρ=150ωcm) with various densities of dislocations (ND = 1 × 104 to 1 × 107 cm −2) introduced at plastic deformation was studied. The temperature dependences of the Hall coefficient were measured. The probabilities of interaction of vacancies with oxygen, phosphorus atoms, and dislocation line elements were determined. It has been established that with the increase of ND they can increase at the expense of complication of dislocation structure, decrease during formation of impurity atmosphere near dislocations and compensation of deformation fields, and they do not change if complex formation of vacancies with impurities occurs far from dislocations. Kinetics of A- and E-centre accumulation in the crystals containing dislocations with different impurity atmosphere was described.

Reconstruction processes proceeding during annealing of radiation defects in60Co γ-ray-irradiated (T in≲50°C) n-type silicon (ρ=20 to 250 Ω cm) grown by the vacuum float-zone technique were investigated. The temperature dependences (80 to 400 K) of charge carrier concentration and life time were measured at various stages of annealing (Tann= 100 to 600°C). It has been established that during annealing theE-centres interact with carbon-containing complexes of interstitial type or are transformated into more complicated complexes of phosphorus-divacancy. Phosphorus electrical activity is completely restored after annealing of phosphorus-divacancy complexes atT ann = 400 to 500°C. The energy level of phosphorus-divacancy complexes was found to be in lower half of forbidden gap (ΔEr = 0.34 eV). The cross-section [sgrave] p of hole capture by these complexes was determined to be equal to 4 × 10−15 cm2. It was concluded that the phosphorus-divacancy complexes are singly charged acceptors.

A method for determining the main parameters (potential barrier ψ for charge carriers, size r, and density N* of electrically active defects) of defect clusters in semiconductors is suggested. This method is based on the experimentally observed variation in the occupancy of defect levels during their localization in defect clusters. The method is used for estimating the parameters of the central (the core) and the peripheral regions of defect clusters forming in n-Si (ϱ0 = 3 to 200 Ωcm) at 660 MeV proton and fast reactor neutron irradiation. Taking into account the results obtained it is concluded that these parameters depend on the irradiation conditions (temperature, energy EAof primarily knocked on atoms) and impurity content. It is shown that the core parameters are determined by EA and those of the periphery are dependent on Eg, irradiation temperature, and impurity content. With EA increase the sizes of defect cluster core and periphery are increased and the defect density within them and the potential barrier height are decreased. On increasing the irradiation temperature and decreasing the impurity concentration in crystals the diffusion length of the mobile primary defects migrating from the primary displacement cascade is increased, on this account the periphery size is increased and ψ and N* are decreased.

The effect of dislocations introduced by plastic deformation (ND = 1 × 102 to 1 × 107 cm−2) on the nonequilibrium carrier recombination processes for different levels of their injection is studied. The charge-carrier lifetime (τ) is measured by means of conductivity modulation at a point contact (T = 300 K) in n-Si (ϱ = 150 Ω cm). With increasing ND, τ is shown either to increase (low-level injection) or to decrease (high-level injection), where this dependence is stronger in crystals with low content of technological impurities. An anomalously drastic decrease of τ with increasing injection level is observed in Si with higher dislocation density. The results obtained are explained taking into account the presence of the potential barrier near dislocations, the magnitude of which, as well as the volume of the dislocation space-charge region depend on NDand decrease with increasing injection level. [Russian Text Ignored.]

Radiation-induced accumulation and annealing processes of radiation defects with level Ec–0,22 eV in silicon of various perfection are analysed and it is concluded that they consist of oxygen and two vacancies (oxygen-divacancy complex).

Comparative experiments are made to study the nonequilibrium charge-carrier recombination in silicon irradiated with γ-rays of 50Co and of the bremsstrahlung spectrum of electrons with maximum energy 100 MeV. n- and p-Si crystals with ϱ = 10 to 1000 Ωcm grown by Czochralski and vacuum float-zone techniques are used. The temperature and injection dependences of nonequilibrium charge-carrier lifetimes measured by a phase method are analyzed. It is found that when irradiating with γ-rays of 60Co a great number of recombination centers are produced which are mainly complexes of irradiation-generated vacancies and interstitials with dopants (phosphorus, boron) and technological (oxygen, carbon) impurities. As distinct from this, the dominant recombination centres in silicon irradiated with γ-rays of the bremsstrahlung spectrum are divacancies involved in defect clusters, surrounded by the potential barrier Ψ for the majority charge carriers. The parameters of recombination centres (energy level spectrum, annealing temperatures, charge-carrier capture coefficients) in crystals studied under γ-irradiation are determined. The peculiarities in the charge-carrier recombination processes due to the localization of recombination centres in defect clusters generated by photonuclear reaction products are discussed. [Russian Text Ignored]

A change in the concentration and charge-carrier lifetime in n-Si when irradiating by high-energy γ-rays was studied and parameters of radiation defect clusters produced by them were determined.

The radiation defect production and annealing processes in dislocated silicon are analysed. The character of the effect of dislocations on the radiation defect parameters is shown to depend on their nature. Taking into account the dependence determined a scheme is suggested in accordance with which the electrically active defects in Si are divided into four groups. This is useful when identifying defects of unknown nature.

The change of charge-carrier concentration and lifetime in high-resistivity float-zone n- and p-Si with equilibrium concentrations of electrons n0=(2 to 30)× 1012 cm−3 and holes p0=(5 to 30)× 1011 cm−3 when irradiating by 60Co γ-rays (T= 330 K) is studied. There is a drastic increase of the initial charge- carrier removal rate and the coefficient for the radiation variation of their lifetime. The results obtained are explained on the assumption of the dependence of the annihilation probability of Frenkel pairs on the charge state of vacancy (V) and interstitial Si atom (I).The energetic position of the levels separating the states I0/I++ and V−/V0 which are at Ec −(0.43−0.45) eV and Ec −(0.47−0.54) eV, respectively, is estimated.

The accumulation processes of the compensating and recombination centres during 60Co γ-ray irradiation of n-type Si (ρ = 50–250 Ωcm, τ = 50–100 μs) with a high dislocation density (N D = 1 ˙ 104−˙−1 ˙ 107 cm−2) introduced by plastic deformation are studied. The results are obtained from measurements of the minority charge-carrier lifetime by the method of conductivity modulation at a point contact and the Hall coefficient temperature dependences. Radiation defect introduction efficiency is found to depend significantly on the content of the dislocation impurity atomosphere whose change is achieved by varying the deformation conditions (fast and slow cooling) and subsequent radiation-heat treatments (γ-ray irradiation and annealing). The experimental results are interpreted taking into account the conception of compensation of elastic stress fields by impurity atoms and participation of impurities in complexing with primary radiation defects near dislocations.

The formation and annealing processes of radiation defects in bulk crystals and thin (≈ 1.2 μm) epitaxial layers of Si are studied. Czochralski grown (pulled) and vacuum float-zone n-type Si crystals with ϱ = 1 to 2 Ωcm as well as n-type Si epitaxial layers (∂ ≈ 1 Ωcm) grown on substrates of p-type Si, 400 pm thick (ϱ ≈ 10 Ωcm) are used. The samples are irradiated (T ⪷ 50 °C) by 640 MeV protons. Results are obtained from the analysis of the temperature dependences of the Hall coefficient at various steps of irradiation or 15 min isochronous annealing as well as from the spatial distributions (over the layer thickness) of the doping impurity and irradiation- and annealing-produced defect concentration. It is established that due to the interaction with the surface of irradiation-generated vacancies and interstitials as well as mobile defects and their components migrating at annealing, a number of peculiarities in radiation defect accumulating and annealing processes take place in epitaxial layers of Si as compared to bulk crystals: 1) Lower charge-carrier removal rates due to the low E-centre introduction efficiency whereby they are not the main compensating defects in thin layers whose thickness is comparable to the vacancy diffusion length; 2) sufficiently wide radiation defect annealing range; 3) effective production of multivacancy complexes under heat treatment near the surface. The results obtained are explained taking into account electric fields and long-range elastic stress fields near the surface. [Russian Text Ignored].

Defauts ponctuels generes par rayonnement γ interagissant avec des agregats impuretes-defauts formes par traitement thermique d'un Si n obtenu par zone flottante irradie par protons de 640 MeV. Analyse des variations en temperature (de 80 a 400 K) du coefficient Hall et de la conductivite electrique. Les taux de creation de defauts dans Si sont interpretes a l'aide de la migration des atomes lacunaires et interstitiels vers ces defauts. Prise en compte du role des champs de contrainte elastique entourant ces agregats

The effect of dislocations introduced at plastic deformation (ND= 1 × 105 to 2 × 107 cm−2) on the activation energy δE of radiation defect thermal ionization in Si is studied. The temperature (80 to 400 K) dependences of the Hall coefficient at various steps of 60Co γ-ray irradiation are mea-sured. A variation in δE is found to take place for point defects accumulating near dislocations (A-centres, divacancies, interstitial carbon-substitutional carbon complex, carbon-oxygen-di-vacancy complex). An increase of δE with ND increasing is characteristic of A-centres, for example, for low integral γ-ray fluxes (Φ ⪅ 5 × 1016 cm−2). This is due to the increase of thermal ionization energy ΔE as a result of shifting of allowed band edges and defect levels, because of the crystal lat-tice deformation near dislocations. In dislocated Si (ND ⪆ 1 × 106 cm−2) on increasing O one ob-serves at first a decrease of δE, and then its increase. It is connected with the formation of radia-tion defect agglomerations near dislocations which have a localize dspatial charge and produce a potential barrier Ψ, whereby δE = ΔE =Ψ. The dose dependences of δE are explained taking into account the variation in Ψ with increasing O and the possibility of defect rearrangements in more complicated complexes near dislocations. [Russian Text Ignored.]

The processes of radiation defect formation in n-type silicon are studied at various irradiation temperatures (Tirr = 20 to 400°C) during 640 MeV proton or 10 MeV electron bombardment. The results are obtained from the analysis of the temperature dependences of charge carrier concentration in crystals irradiated at various temperatures and investigating samples (which are not irradiated but subjected to similar thermal treatment). It is established that production efficiencies for main radiation defects (A-, E-centres, divacancies, complexes of carbon–oxygen-divacancy) are complicated functions of Tirr, however the form of these functions appear to be different for the two types of irradiation used. The results obtained are interpreted taking into account the fact that during cascade defect formation (in the case of proton irradiation) the effect of Tirr is due to the probabilities of secondary processes (dissociation and formation of complexes) changing with temperature, while in the case of diffusive mechanism (electron irradiation) the irradiation temperature Tirr has also an influence on the direct annihilation of Frenkel pairs generated by irradiation. [Russian Text Ignored].

Peculiarities in accumulating and annealing processes of 60Co γ-ray-induced radiation defects of vacancy (E-centers) and interstitial (interstitial carbon C1, complexes of substitutional carbon-interstitial carbon Ci-Cs) types due to their interaction with defect clusters being formed under heat treatment of n-Si preliminarily irradiated by fast neutrons have been studied.

Recombination processes of nonequilibrium charge carriers at dislocations introduced at plastic deformation (Tdef = 750 °C) and radiation defects being generated by 60Co γ-rays (Tirr ≦ 50 °C) are studied. p-type Si single crystals (ϱ = 20 to 1500 Ω cm) are used grown by the float-zone as well as by the Czochralski techniques. The lifetime (τ) of minority charge carriers is measured (Tmeas = 300 K) by the method of conductivity modulation at a point contact at different stages of plastic deformation and irradiation. The established regularities of the τ variation with increasing dislocation density (ND) for different charge-carrier injection levels (Δp/p0) in plastically deformed and irradiated Si are explained on the basis of the model developed taking into account the presence of space charge regions near dislocations which produce potential barriers and wells for holes and electrons. This stipulates a spatial separation of nonequilibrium charge carriers and results in a decrease of their recombination rate at radiation defects distributed in the crystal matrix and accumulated near dislocations. The potential barrier height depends on ND and Δp/p0 and varies during irradiation due to the interaction of primary radiation defects with dislocations and changes in the dislocation structure. [Russian Text Ignore]

Rearrangement processes proceeding during annealing of electrically active radiation defects in heavily irradiated (30 MeV protons) Si when the concentration of primary defects induced exceeds the concentration of impurities available in crystal are studied. Czochralski grown and vacuum floating-zone n- and p-type silicon (ϱ = 3 to 500 Ω cm) are used. Experimental results obtained from the analysis of the Hall coefficient temperature dependences show that the rearrangement of intrinsic structural defects (diinterstitials and multivacancy complexes) occurs predominantly during annealing. Accumulation kinetics is studied and temperature stability range of some multivacancy complexes contributing to the forbidden gap energy levels Ev + 0.29 eV (400 to 650 °C), Ev + 0.32 eV (500 to 750 °C), Ev + 0.22 eV (500 to 700 °C), Ev + 0.15 eV (500 to 800 °C), Ev + + 0.10 eV (600 to 750 °C), Ec −0.24 eV (500 to 850 °C) most of which are acceptor levels is determined. The diinterstitial (Si-B3) center being annealed in the temperature range 300 to 500 °C is supposed to be a multicharge defect and has deep acceptor ( Ec −0.40 eV) and donor ( Ev + 0.35 eV) levels. [Russian Text Ignored]

Changes in the Hall coefficient and Fermi level (EF) at T = 300 K as a function of the flux (Tirr ≦ 50°C) of 60Co and stopping spectrum (Emax = 100 MeV) γ-rays, electrons (2.5 to 10 MeV), protons (640 MeV), and fast reactor neutrons in float-zone and pulled n- and p-type Si are studied. It is found that for all kinds of irradiation, the floated zone n-type Si changes the type of its conductivity and a Fermi level stabilization takes place within some range of particle fluxes at Ev + 0.48 eV (proton and neutron irradiation) or at Ev + 0.39 eV (60Co γ-rays, electrons). The Fermi level stabilization at Ev + 0.48 eV is concluded to be determined by the accumulation at dominant concentrations of divacancies having donor, (Ev + 0.28 eV), and acceptor, (Ec −0.40 eV), levels in the forbidden gap and the Fermi level stabilization at Ev + 0.39 eV the accumulation of multicharge complexes involving primary radiation defects and residual impurities (possibly, carbon). The Fermi level position near the middle of the forbidden gap at Ev + (0.54 ± 0.03) eV, which is achieved during prolonged irradiation, is due to the accumulation of vacancy and interstitial types of intrinsic structural damages, being annealed at T = 80 to 150°C. [Russian Text Ignored].

The effect of dislocations introduced at plastic deformation (ND = 1 × 105 to 2 × 107 cm−2) on the radiation defect production and annealing processes in n- and p-type Si single crystals (g = 20 to 1500 ω cm) irradiated (Tirr ≦ 320 K) by γ-rays of 60Co or 640 MeV protons is studied. The temperature dependences of the Hall factor and the electrical conductivity are measured. It is found that the introduction efficiency and temperature stability of some defects are changed due to the higher dislocation density available in crystals. The results obtained are interpreted taking into account the fact that the elastic stress fields available around dislocations, which cause the vacancies and interstitial atoms to migrate towards dislocations, play the determining role for the radiation defect formation. Thereby two competitive processes proceed near dislocations: disappearance of the primary radiation defects and their participation in complex production. As a result, a decrease in the introduction rates of A-, E-centers, interstitial carbon, and the formation of a dislocation-impurity-defect atmosphere which comprises A-centers, divacancies, oxygen-car-bon-divacancy complexes, and defect cluster regions obtained during the proton irradiation, is found. [Russian Text Ignored].

A model of nonequilibrium charge-carrier recombination in semiconductors with nonuniform inclusions is suggested which takes into account the fraction of the crystal volume occupied by them and the bending of the potential relief near them. The use of the model conceptions developed allows to explain correctly some experimental results which does not seem to be possible within the framework of the Hall-Shockley-Read statistics or the theory of charge-carrier recombination in nonuniform semiconductors. [Russian Text Ignored].

Charge carrier recombination in n-type Si (ρ = 10-1000Ω · cm) irradiated by y-rays of stopping spectrum with the maximum quantum energy Em = 100 MeV has been studied. It has been found from the measurements of dose, temperature and injection dependences of carrier lifetime (τ) that the main recombination centers which are formed under such irradiation are the divacancies involved in radiation defect (RD) clusters. It has been shown that the dependence of the coefficient for radiation damage of τ on crystal doping level obtained in experiment cannot be described within the framework of the known models of the carrier recombination at RD clusters. Recombination statistics have been proposed which take into account not only the height of potential barrier around a RD cluster but the relation K s between the volumes of outer and inner charges of RD clusters. Recombination rate at the defects in the cluster is assumed to increase by a factor of K s as compared to recombination rate at the same number ...

The annealing mechanism of divacancies involved in radiation defect clusters is suggested in accordance with which the interaction of interstitial carbon atoms and intrinsic diinterstitials, mobile at T≳ 100°C, with divacancies results in their smooth annealing in a wide temperature range.

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 ...

The change of charge-carrier concentration is studied when irradiating floated zone n- and p-type Si with ϱ = (1 to 5) × 102 and (1 to 60) × 103 ω cm by high fluxes of 60Co γ-rays (Φe = 1 × 1017 to 2 × 1019 cm−2) and electrons with energy Ee = 4 to 10 MeV (Φe = 1 × 1015 to 5 × 1016 cm−2). The temperature dependences of the Hall coefficient are measured. The analysis of the results on the accumulation under irradiation and annealing of radiation defects allows one to conclude that various trends of the dose dependences of hole concentration with the kinds of bombarding particles used are due to the difference in the production efficiencies of radiation defects under electron and γ-ray irradiation. The possibility of formation of phosphorus-two vacancy complexes by adding vacancies to E-centres during prolonged γ-irradiation is shown while electrons produce preferentially divacancies. Phosphorus-two vacancy complexes are stable up to T = 400 to 500 °C and introduce a deep acceptor level at Ev + 0.35 eV into the forbidden gap of Si. It is found that the annealing character of radiation defects in heavily irradiated Si does not depend on the kind of irradiation and is due to the rearrangements of intrinsic structural defects. [Russian Text Ignored].

The effect of dislocations (ND = 1 × 104 to 2 × 107 cm−2) on radiation defect annealing processes in n- and p-type Si grown by the Czochralski as well as the vacuum float-zone techniques (ϱ = 20 to 1500 Ωcm) is studied. The experimental results are obtained from the analysis of the temperature (80 to 400 K) dependences of the Hall coefficient measured before and after irradiation and at various steps of isothermal or 15 min isochronous annealing. It is established that with the higher dislocation density available in crystals and lattice distortion produced by them a decrease in annealing temperature, activation energy, and values of frequency factor takes place for the defects (A-centers, divacancies, oxygen–carbon–divacancy complexes, carbon-containing defects with level Ec −0.17 eV in float-zone n-type Si), which are produced near dislocations and constitute their impurity–defect atmosphere. The defects (E-centers, interstitial carbon) which are produced far from dislocations are characterized by the change of their annealing kinetics due to the directed migration of E-centers and interstitial carbon towards dislocations when affected by elastic stress fields. The role of dislocations in the processes of rearrangement and spatial redistribution of radiation defects at annealing is shown. [Russian Text Ignored].

The influence of the irradiation kind and dislocation density on the rearrangement processes at annealing of radiation defects of different types has been studied.

The effect of dislocations on nonequilibrium charge carrier recombination in irradiated Si has been studied and the model providing satisfactory explanation of the experimental results has been proposed.