THE STUDY OF POSITRON-ANNIHILATION IN ELECTRON-IRRADIATED TYPE IA DIAMOND

To form Vacancy-defects, a type Ta diamond single crystal with a nitro gen impurity in different forms was 3.5 MeV electron-irradiated with i ncreasing doses of 5 x 10(16), 2 x 10(17), 4 x 10(17) and 2 x 10(18) e /cm(2). After each dose the specimen was investigated by positron anni hilation (ACAR). EPR and optical spectroscopy in visible and IR region s. By the direct method of positron annihilation the formation of vaca ncies in neutral and negative charge states was established in the spe cimen. Specific trapping rates and trapping cross-sections of position s of both defects were estimated. (C) 1998 Elsevier Science S.A.