Positron trapping at thermal vacancies in highly As-doped Si

Using positron annihilation measurements we observed the formation of thermal vacancies in highly As-doped Si. The vacancies form already at 700 K and upon cooling down the vacancies form stable vacancy-impurity complexes such as V–As3V–As3. Only a fraction of thermal vacancies is observed during equilibrium temperature measurements, but the quenching to room temperature reveals that the concentration of thermally generated V–As3V–As3 defects is an order of magnitude larger. This mismatch is explained by positron detrapping from V–As3V–As3 at high temperatures.