Investigation of the magnesium impurity in silicon

The diffusion profiles of the concentration of electrically active and total concentrations of the magnesium impurity in silicon are measured. Diffusion is carried out by the sandwich method into FZ dislocation-free $n$-type silicon at the temperatures $T_{\operatorname{diff}}$ = 1000 and 1100$^\circ$С, and at a process duration from 0.5 to 22.5 h. The concentration profiles $N_{\mathrm{Mg_i}}(x)$ of the electrically active magnesium component are determined by the differential-conductivity method, and the total-concentration profiles $N_{\operatorname{total}}(x)$, by secondary-ion mass spectroscopy. It is established that the total concentration of magnesium in the samples is $\sim$2 orders of magnitude higher than that of the electrically active component. It is also found that the diffusion coefficient $D_{\mathrm{Mg_i}}$ of interstitial magnesium depends on the diffusion time and decreases with an increase in the duration of the process. Assumptions are made about the physical processes, which can lead to the formation of an electrically inactive component of magnesium impurity and to the dependence of the effective diffusion coefficient on time.