Scandium correlated deep levels in silicon

Deep band-gap states in silicon were studied by deep level transient spectroscopy during the elemental transmutation of the radioactive isotope Ti-45 to S-c. The parent isotope Ti-45 was implanted into n- and p-type silicon by recoil implantation using the nuclear reaction (SC)-S-45(p,n) Ti-45. Repeated measurements reveal a concentration decrease of the three well-known levels of interstitial titanium in Si and an increase of three levels at 0.21, 0.47, and 0.50 eV below the conduction-band edge. Since the concentration versus time curves exactly reflect the nuclear transmutation (half-life 3.08 h), these new levels are identified to be scandium correlated. Since an involvement of other defects is unlikely, these levels are most probably associated with different charge states of interstitial Sc in Si. (C) 1996 American Institute of Physics.