Implantation and Annealing Behavior of Group III and V Dopants in Silicon as Studied by the Channeling Technique
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abstract
The implantation and annealing behavior of several Group III (Ga, In, Tl) and Group V (As, Sb, Bi) dopants in silicon has been investigated by studying the orientation dependence of the scattering yield of a 1.0-MeV He+ beam. This orientation dependence (``channeling'') provides quantitative information on the location of the foreign atoms in the lattice, and also on the amount of lattice disorder introduced by the implantation. The behavior of the Group V elements is relatively simple. In hot (350°–450°C) implants and also in annealed room-temperature implants, the dopant atoms are located mostly on substitutional sites, even for implant doses exceeding equilibrium solubility values by 1–2 orders of magnitude. Upon subsequent anneal, no evidence of precipitation is observed below ∼900°C. The behavior of the Group III elements is much more complex. In addition to a substitutional component, a significant fraction of the implanted atoms are located in the regular interstitial holes along the (111) atomic rows. The substitutional/interstitial ratio in hot implants is usually 1:1, except in the case of Tl implants where, on annealing to ∼575°C, a pure interstitial component is observed. Furthermore, the subsequent annealing behavior is found to depend markedly not only on the particular Group III ion, but also on the implantation temperature. Various factors that may contribute to the Group III behavior are discussed. Preliminary ion implantation studies with other elements (Cd, Sn, Te, Xe, Cs, and Au) in silicon have been included.
