Positron trapping kinetics in thermally generated vacancy donor complexes in highly As-doped silicon

We have measured positron lifetime and Doppler broadening in highly As-doped silicon containing thermally generated V−As3 defect complexes (vacancy is surrounded by three arsenic atoms). We observe positron detrapping from the V−As3 defect complex and determine the binding energy of 0.27eV of a positron to the complex. The results explain why 85% of the thermal vacancies formed in highly As-doped Si at temperatures over 700K are invisible to positron measurements at elevated temperatures.