No abstract

532.546Based on the modification of the "exact-on-average" method, simple analytical formulas have been found for calculation, in the zero and first asymptotic approximations, of pressure fields in an inhomogeneous anisotropic bed in constant drainage for the case of one-dimensional linear flow. The results of calculations of the fields from the obtained formulas have been given.

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.

No abstract

Nonequilibrium carrier recombination processes are studied in n‐Si (ϱ = 100 to 250 Ωcm) containing higher density of dislocations introduced at plastic deformation (ND = 1 × 103to 1 × 107 cm−2) and after irradiation with 60Co γ‐rays. The experimental results are obtained from the measurements of minority carrier lifetime (τ) by the method of conductivity modulation at a point contact. τ is shown to be very sensitive to the presence of dislocations in crystals. The dependences of τ on NDobserved in the experiment are described taking into account an increase in the effective cross‐section of hole capture at dislocation dangling bonds. When irradiating dislocated crystals a decrease in τ is observed and in some cases, with γ‐flux increase, τ increases, too. The coefficient of radiation variation in τ in crystals with various dislocation densities is determined. The results obtained are explained taking into account the fact that the irradiation‐induced radiation defects are not only additional recombination centers but that they change the dislocation recombination activity as well.