Abstract:
Precipitation of boron implanted in silicon with a dose of 1 $\times$ 10$^{16}$ cm$^{-2}$ is studied in relation to the concentration of substitutional boron $C_{\mathrm{B_0}}$ introduced before implantation and before subsequent annealing at 900$^\circ$C. It is shown that $C_{\mathrm{B_0}}$ = 2.5 $\times$ 10$^{20}$ cm$^{-3}$ is the critical concentration, at which the formation of precipitates is independent of the concentration of point defects introduced by implantation (far from or close to the mean projected range $R_p$) and constitutes the prevailing channel of deactivation of boron. At lower concentrations $C_{\mathrm{B_0}}$ close to the equilibrium concentration, precipitation is observed only far from $R_p$, in the regions of reduced concentrations of point defects. At the same time, in the region of $R_p$ with a high concentration of point defects, most boron atoms are drawn into clustering with intrinsic interstitial atoms with the formation of dislocation loops and, thus, become electrically inactive as well.
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