Positron lifetime and Doppler broadening studies were reported. It was found that, in as-grown Czochralski Si, vacancies were retained in concentrations that were typically equal to about 3 x 1016/cm3. The 10MeV electron irradiation of variously doped Si wafers showed that only dopant concentrations that were well above the interstitial O concentration caused an increase in the numbers of mono-vacancies which were retained. In the case of porous Si, very long-lived positronium lifetimes (40 to 90ns) were found. The polycrystalline diamond films contained various types of vacancy agglomerate, but these were found to be inhomogeneously distributed from crystallite to crystallite. The electron irradiation of SiC produced 2 vacancy-related lifetimes which were attributed to C and Si vacancies.

S.Dannefaer: Applied Physics A, 1995, 61[1], 59-63