Dependence of trapping and segregation of indium in silicon on the velocity of the liquid-solid interface

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Abstract
The segregation phenomena of In-implanted Si have been observed following the melting and epitaxial regrowth of surface layers by pulsed ruby laser irradiation. The velocity of the liquid-solid interface on recrystallization has been varied from 1.8 to 5.2 m/s in two independent ways. Indium is observed to be trapped on substitutional sites, in excess of solid solubilities, or segregated in a thin surface layer. Trapping increases and segregation decreases as the interfacial velocity is raised. The complete depth profiles can be fitted with unique interfacial segregation coefficients which are velocity dependent. The material that has been segregated to the surface shows cell structure of approximately 100 Å diameter arising from lateral segregation due to constitutional supercooling. The cells are not present at velocities of 5 m/s. The critical dependence of In trapping and segregation on velocity in the range 2–5 m/s is interpreted in terms of interfacial residence times.