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A study was made of the introduction rate of radiation defects Δ N d e f / Δ D versus the fast electron irradiation dose ( D ) in semiconductor crystals of n-Si and n-GaP. We take the concentration of radiation defects concentration N d e f to be the difference between the carrier concentration of semiconductors before n0 and after irradiation n ( D ) at the dose D , delivered at room temperature. By application of an appropriate fitting function to the dose dependent curves of the N d e f ( D ) , it was demonstrated that the empiric exponential law of the form N d e f = n 0 ( 1 − exp ( − D / D 0 ) ) gives the best agreement with the experimental data, irrespective of the electron energy and irradiation dose. D 0 is the irradiation dose, at which the carrier concentration n ( D ) at a temperature T = 300 K decreases by a factor of e. The results showed that the formation of radiation defects in the samples studied is not a linear process and Δ N d e f / Δ D are found to decrease exponentially with increasing irradiation dose, according to their particular character. Using the same fitting method, it was found that for certain samples, beyond a particular radiation dose level, the rate of carrier mobility versus radiation dose also decreased exponentially. |
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