A comparative study is made on the radiation damage caused by fast-pile neutrons in n-Si with low and high concentrations of oxygen by measuring the effective carrier concentrations and energies of defects. The role of clusters in degrading Si parameters was studied both experimentally and theoretically. It has been shown experimentally that the fluence for which the carrier concentration tends to the intrinsic value does not depend on the oxygen concentration. The theoretical calculation has been carried out in the framework of Gossick's corrected model. The additional overlapping of clusters due to introduce of defects is explained. The model of the n → p conversion in n-Si with various oxygen concentrations is presented. It is shown that divacancy and di-interstitial congestions are responsible for the Fermi level position near the midgap at high fluences. Analysis of V ξ defect levels gave evidences of increase of level energy in the forbidden band on capture of the first or the second electron on the value ∆E = 0.33/ξ, where 1 ≤ ξ ≤ 5.

Phosphorus‐doped silicon samples grown by various methods after irradiation by fast neutrons of a WWR‐M reactor and subsequent annealing at room temperature were investigated. The calculation of the temperature dependence of effective carrier concentration was carried out in the framework of Gossick's model, taking into account the recharges of defects both in the conducting matrix of n‐Si and in the space charge region of defect clusters. The distribution function of electrons in the acceptor level of bistable defect (CiCs)0 was determined in the case when the concentration of this defect is a function of the Fermi level in the conducting matrix of n‐Si. The concentration of bistable CiCs defect and its energy level at (Ec – 0.123 eV) in the forbidden band of silicon were calculated. The absence of reconciliation between the introduction rate of A‐centers in n‐Si, irradiated by fast neutrons of the reactor, and the concentration of oxygen in 1016–1018 cm–3 limits was determined. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A variety of high purity silicon grown on the basis of different manufacturing technologies were exposed to gamma irradiation (up to a dose of 10' rad(Si)) and to neutron irradiation (up to a fluence of 10'' n/cm*). Observation was made of the conduction type and carrier concentration as a function of dose. The conversion point (n-Si to p-Si) of gamma jxradiated silicon was found to vary over 2 orders of magnitude of gamma dose for different manufacturers of high purity silicon independent of the initial carrier concentration. A systematic study of the radiition hardness of high punty silicon allows the development of silicon detectors working under harsh radiation environments operating over a wide range of dose. Another important aspect of this research is the development of neutron dosimeters with a wider range of response in terms of 1 MeV(Si) equivalent neutron fluence for calibration of neutron test facilities with unknown neutron energy spectrums. High punty silicon PIN diodes were calibrated using an epithermal neutron beam to determine whether response in terms of 1 MeV(Si) neutrons was independent of the calibration spectrum used.

Irradiated n-Si with Layer InhomogeneityIn /1/ experimental data on the anisotropy of galvanomagnetic effects in diated n-Si with layer inhomogeneity were presented. The results on the anisotropy of the transverse magnetoresistance in I -irradiated n-Si samples which were differently cut with respect to the impurity layers permitted to conclude about the complete suppression of anisotropy effects connected with the anisotropy of the charge carrier effective mass in the n-Si conduction band. The observed anisotropy of magnetoresistance in this case is connected with a periodic distribution of phosphorus atoms in the silicon lattice. In the present communication we give data on quantum oscillations of the current after 7-irradiation in the same samples cut at different angles relative to the impurity layers under conditions similar to that of /l/: T = 77 K, B = 16 kG, 8x10 rad, and present an interpretation of all observed experimental data. The experimental procedure is described in detail in /2/. The main point is that the sample is turned in a constant magnetic field around its axis along which the sample current flows; the magnetic field vector 6 is always perpendicular to the current vector J. The angle of sample rotation ' p relative to the vector 5 in all samples is counted from the CflOl direction. In Fig. 1, on the left, the dependence of current in each sample on rotation angle ' p is shown; on the right, the sample positions for 'p = 90' are indicated and impurity layer lines are drawn formed by the layer distribution of phosphorus atoms.is the angle between the current direction and the impurity layer planes in each sample. The voltage applied to the sample is constant during the measurement and equal to w 2.0 V. Before 3 -irradiation in all samples current oscillations are observed (Fig.