Diffusion of interstitial magnesium in dislocation-free silicon

Abstract

The diffusion of magnesium impurity in the temperature range T = 600–800°C in dislocation-free single-crystal silicon wafers of p-type conductivity is studied. The surface layer of the wafer doped with magnesium by the ion implantation technique serves as the diffusion source. Implantation is carried out at an ion energy of 150 keV at doses of 5 × 10¹⁴ and 2 × 10¹⁵ cm^–2. The diffusion coefficient of interstitial magnesium donor centers (D_i) is determined by measuring the depth of the p–n junction, which is formed in the sample due to annealing during the time t at a given T. As a result of the study, the dependence D_i(T) is found for the first time. The data show that the diffusion process occurs mainly by the interstitial mechanism.