Features of the behavior of lanthanum and hafnium atoms in silicon

Features of the interaction of lanthanum (La) and hafnium (Hf) atoms in single crystal silicon have been studied using a differential capacitance (deep-level transient spectroscopy) technique. Hf atoms introduced into silicon by diffusion form two deep levels with the ionization energies E _c-0.28 eV and E _v + 0.35 eV. La atoms introduced into silicon in the course of single-crystal growth from melt exhibit no electrical activity. However, the presence of La atoms in silicon increases the efficiency of formation of the impurity levels related to the subsequent diffusion doping with hafnium and, in addition, leads to the stabilization of these levels: the annealing of Hf-related levels proceeds at a much lower rate in Si〈La,Hf〉 than in Si〈Hf〉 crystals.