Controlling the density distribution of SiC nanocrystals for the ion beam synthesis of buried SiC layers in silicon

The depth distribution of SiC nanocrystals formed during high-dose implantation of carbon ions into silicon at conditions suitable for the ion beam synthesis of buried SiC layers in silicon is studied in this paper. For implantation temperatures of 400-600 degrees C and dose rates of 10(12) - 10(13) C+/cm(2)s, SiC precipitates in crystalline silicon are observed to be of approximately equal size, independent of the depth position beneath the surface. Ballistic destruction of small precipitates and difficulties in precipitate growth are thought to be responsible for the observed narrow size distribution. The destruction of precipitates may lead to the simultaneous release of a superthreshold concentration of carbon atoms resulting in a carbon-induced amorphization of the silicon host lattice. The local reduction of the number density of SiC nanocrystals involved with this amorphization can be used to tailor discontinuous depth distributions of oriented SIC precipitates providing ideal starting conditions for the synthesis of well-defined single-crystalline SiC layers in silicon. (C) 1999 Elsevier Science B.V. All rights reserved.