Dopant effect on point defect incorporation into growing silicon crystal

Abstract

Acceptor and donor dopants affect the critical ratio v/G for the change-over from interstitial to vacancy incorporation (v is the growth rate and G is the near-interface temperature gradient) in growing silicon crystals. The boron effect (an increase in the critical v/G) is nicely accounted for by a simple mechanism of electronic shift in the equilibrium concentrations of the charged point defects at the melting point (Tm). By fitting the theoretical curve to the experimental data, the ratio of the equilibrium concentrations of vacancy and self-interstitial is defined to be 1.3 at Tm. Given this the interstitial diffusivity and the two equilibrium concentrations at Tm can then be specified. Beside the electronic shift, alternative mechanisms (interstitial impurity component, impurity pairing to vacancy) are discussed to provide a general formula for the impurity-induced shift in the critical v/G. © 2000 American Institute of Physics.