RECOMBINATION ACTIVITY OF MISFIT DISLOCATIONS IN SILICON

A study of misfit dislocations in Si using the techniques of electron beam induced current (EBIC) and cathodoluminescence (CL) is presented. The dislocation recombination properties are found to depend on contamiiation. Dislocations in clean, as grown samples without D-band luminescence have very low recombination activity, with an EBIC contrast c of about 0.3% at T = 80 K and without detectable contrast at 300 K. Ni contamination is shown to increase the dislocation contrast markedly and to lead to pronounced dark spots at 300 K. A negative c(T) slope is observed for dislocations, which is attributed to shallow centres. Another contrast mechanism acting at the dark spots is ascribed to charged Ni silicide particles. Dark CL dislocation contrast is observed at 5 K when using the substrate luminescence, caused by dislocation-related reduction of exciton density. CL and EBIC correlate in a semi-quantitative manner for all samples studied, suggesting that the same centres might be responsible for the CL and EBIC contrasts.