PRECIPITATION, AGGREGATION, AND DIFFUSION IN HEAVILY ARSENIC-DOPED SILICON

The precipitation and dissolution of monoclinic SiAs, in Si samples im planted with 1 and 1.5 X 10(17) As+/cm(2), was followed at 800, 900, a nd 1050 degrees C by transmission electron microscopy (TEM) and second ary neutral mass spectrometry. It has been found that the concentratio n C-sat of mobile As, which diffuses after equilibration with the mono clinic SiAs precipitates, is given by C-sat=1.3 X 10(23) exp(-0.42/kT) cm(-3), where kT is in eV. This saturation concentration includes dif ferent states of As in equilibrium with the monoclinic phase at the an nealing temperatures, namely, (i) the electrically active and (ii) the inactive mobile dopant. The results presented in this paper indicate that the inactive As is in the form of clusters. The link between the clustering phenomenon and the presence of small particles detected by TEM observations is also discussed.