SCANDIUM CORRELATED DEEP LEVELS IN SILICON

Deep band-gap states in silicon were studied by deep level transient s pectroscopy during the elemental transmutation of the radioactive isot ope 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 i ncrease of three levels at 0.21, 0.47, and 0.50 eV below the conductio n-band edge. Since the concentration versus time curves exactly reflec t the nuclear transmutation (half-life 3.08 h), these new levels are i dentified to be scandium correlated. Since an involvement of other def ects is unlikely, these levels are most probably associated with diffe rent charge states of interstitial Sc in Si. (C) 1996 American Institu te of Physics.