NATURE OF DAMAGE IN DIAMOND IMPLANTED AT LOW-TEMPERATURES

The most effective scheme for electrically activating ion implanted do pants in diamond involves implantation at low temperatures (T-i less t han or similar to 300 K) followed by rapid thermal annealing. For such implantations, all defects (both vacancies and interstitials) are bel ieved to be ''frozen in'', a fact which facilitates subsequent anneali ng. In the present work, the nature of the defects introduced into dia mond by low temperature implantations is determined by combining chann elling, electrical conductivity, swelling and Raman measurements on ty pe IIa diamonds irradiated with 320 keV Xe ions at T-i = 150 K over th e dose range 1 x 10(13)-2 X 10(16) Xe cm(-2). The critical dose for am orphization was found to correspond to an energy deposited in the modi fied layer of 5.5 eV per C target atom. The carriers were determined t o be holes for these cold implantations. The measurements suggest that isolated point defects in diamond behave as accepters, whereas more c omplex agglomerated defects behave as donors.