CHARACTERIZATION OF VACANCIES IN AS-GROWN AND IRRADIATED DIAMONDS

Three types of diamonds were investigated by means of positron annihil ation and optical absorption: Ib (natural), Ib (synthetic) and IIa (na tural). All of the as-grown samples contained vacancy clusters to whic h no optical absorption has been assigned. In Ib (nat), there was an a dditional contribution from monovacancies most probably in the form of 3N. V complexes. In 2-MeV electron-irradiated IIa diamonds, neutral v acancies were produced, whereas in Ib (syn), they were negatively char ged. Optical measurements corroborate the charge assignment of the mon ovacancies. (C) 1998 Published by Elsevier Science S.A.