Precipitation, aggregation, and diffusion in heavily arsenic-doped silicon

The precipitation and dissolution of monoclinic SiAs, in Si samples implanted with 1 and 1.5×{}10¹⁷ As⁺/cm², was followed at 800, 900, and 1050 ^∘{}C by transmission electron microscopy (TEM) and secondary neutral mass spectrometry. It has been found that the concentration Cₛₐₜ of mobile As, which diffuses after equilibration with the monoclinic SiAs precipitates, is given by Cₛₐₜ=1.3×{}10²³ exp(-0.42/kT) cm^-3, where kT is in eV. This saturation concentration includes different states of As in equilibrium with the monoclinic phase at the annealing 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.