Perturbed angular correlation studies of dopant atom interactions in silicon

Abstract

The perturbed γγ angular correlation (PAC) technique was used to study the interaction of implanted 111 In probe atoms with the donor atoms P, As, and Sb in Si. Nearest-neighbor pairs of In-P, In-As, and In-Sb atoms, characterized by νQ1 =179(1), 229(1), and 271(1) MHz, respectively, and having trigonal symmetry about a 〈111〉 axis (η1 =0), were observed after annealing the samples between 540 and 1170 K. These results indicate a strong interaction between acceptor and donor atoms in Si, thus explaining the present and earlier Rutherford backscattering-channeling results that the In atom solubility in Si was enhanced by the addition of As. The In-donor atom binding energy was about 0.5 eV. For increasing As concentrations, PAC data showed the appearance of small In-As atom clusters characterized by νQ2 (As)=238(1) MHz, η2 = 0.65(1); they were probably In-As2 complexes produced when mobile In atoms were trapped by As2 pairs.