Positron scattering on point and line defects in semiconductors

Positron scattering at point and linear defects in semiconductors for quasielastic character of interaction is considered. Formulae for calculation of positron thermalization time on charged impurities, neutral atoms of impurity, point defects (impurities with deep levels) and dislocations are obtained. Estimation of effective thermalization time tau sub(t.eff.) in the temperature range T<=10K, when positron scattering on optical and acoustic photons is practically absent gave for Ge the value 10sup(-11)s that is approximately an order lower than the shortest positron life time in this semiconductor. Conclusion of the theory on positron thermalization in Ge at superlow temperatures agrees with present experimental data