The effect of oxygen on segregation-induced redistribution of rare-earth elements in silicon layers amorphized by ion implantation

A model of segregation-induced redistribution of impurities of rare-earth elements during solid-phase epitaxial crystallization of silicon layers amorphized by ion implantation is developed. This model is based on the assumption that a transition layer with a high mobility of atoms is formed at the interphase boundary on the side of a-Si; the thickness of this layer is governed by the diffusion length of vacancies in a-Si. The Er concentration profiles in Si implanted with both erbium and oxygen ions are analyzed in the context of the model. It shown that, in the case of high doses of implantation of rare-earth ions, it is necessary to take into account the formation of R_m clusters (m = 4), where R denotes the atom of a rare-earth element, whereas, if oxygen ions are also implanted, formation of the complexes RO_n (n = 3–6) should be taken into account; these complexes affect the transition-layer thickness and segregation coefficient.