Electronic structure of silicon carbide containing superstoichiometric carbon

Electronic structure of superstoichiometric silicon carbide, ß-SiCx>1.0, was studied by the self-consistentab initio linearized “muffin-tin” orbital method. It is most likely that the formation of ß-SiCx>1.0 occurs by replacement of silicon atoms by carbon atoms rather than by insertion of carbon atoms into interstitial lattice sites. The C→Si replacement is accompanied by lattice compression (the equilibrium lattice parameter for a superstoichiometric phase of composition Si0.75C1.25 is −2% smaller than for SiC). In the presence of superstoichiometric carbon the type of interaction between silicon and carbon atoms changes and additional bonds characteristic of diamond are formed.