Electrically active centers in silicon doped with erbium

Making use of Hall effect measurements we determined some characteristics of centers formed in Si by means of diffusion and ion implantation. It has been shown that the diffusion of Er in Si at high temperatures (1100 degrees-1250 degrees C) leads to the formation of shallow acceptor centers at approximate to E(V) +45 meV. The concentration of these accepters is largely governed by the type and concentration of intrinsic point defects dominating during an annealing at high temperatures. The data obtained allow to conclude that the acceptor centers may be substitutional Er atoms. Analysis of the electrical data on FZ-Si following the ion implantation of Er suggests the appearance of donor states at approximate to E(C) -30 meV, approximate to E(C) -50 meV, and approximate to E(C) -90 meV. After the implantation of Er in Cz-Si and co-implantation of Er and O in FZ-Si, three kinds of donor states over the energy interval from E(C) -30 meV to approximate to E(C) -40 meV and at approximate to E(C) -60 meV and approximate to E(C) -90 meV make their appearance. Variations in the annealing temperature exert a remarkable effect on concentrations of these donors. The donor states are thought to belong to some Er-related complexes whose structures are similar to those of oxygen-related thermal donors in Cz-Si.