Some mechanisms of the influence of preliminary heat treatments on the behavior of the parameters of silicon during irradiation

The methods of optical and capacitance spectroscopy, transient photoconductivity, Hall effect, and scanning electron microscopy were used in an investigation of the influence of preliminary heat treatments at 400-1,200 C on the behavior of the parameters of Si single crystals during the subsequent irradiation with γ rays, electrons, or neutrons. An analysis of the experimental results was used to propose five main mechanisms of the influence of preliminary heat treatments of Si on its properties when subjected to ionizing radiations: (1) precipitation of solid solutions of impurities interacting strongly with radiation defects; (2) formation of electrically active thermal defects in concentrations sufficient to alter significantly the charge state of radiation defects; (3) formation of thermal defects capable of interacting strongly with radiation defects; (4) changes in the efficiency of internal gettering of radiation defects as a result of a redistribution of impurities by heat treatments; (5) formation of clusters of electrically active thermal defects, resulting in an electrical inhomogeneity of Si crystals