Vacancy-type defects in heavily phosphorus-doped Si epitaxial films were probed by monoenergetic positron beams. Doppler broadening profiles of the annihilation radiation and lifetime spectra of positrons were measured for the epitaxial films grown on the Si substrates by plasma chemical vapor deposition. For the as-deposited film, divacancy-phosphorus complexes were found with high concentration. After 600° C annealing, vacancy clusters were formed near the Si/Si interface, while no drastic change in the depth distribution of the divacancy-phosphorus complexes was observed. By 900° C annealing, the vacancy clusters were annealed out
however, the average number of phosphorus atoms coupled with divacancies increased. The relationship between the vacancy-type defects probed by the positron annihilation technique and the carrier concentration was confirmed. © 1994 IOP Publishing Ltd.