Space- and ground-based crystal growth of doped InSb

Abstract

Numerical simulations were performed to determine the effect of residual microaccelerations on the distribution of dopants (Te and Zn) during solidification of InSb in space. A "moving geometry" model was developed and used to account for the reduction in melt size during growth. The model demonstrates that diffusion controlled segregation in doped InSb can be obtained at 10-5 g0 gravity for the considered growth parameters. The results for the moving geometry and semiinfinite melt domain models are compared to each other and to the analytical correlations for the case of diffusion-controlled segregation.

A study of segregation during directional solidification of InSb in space and on Earth is presented in this work. Ground-based crystal growth experiments were prepared as a part of SUBSA project (Solidification Using a Baffle in Sealed Ampoules), to provide the reference data for analysis of the space experiments. InSb crystals were doped with Te or Zn. The dopant concentration was measured using Hall Effect, 4-point probe and Atomic Absorption methods. Parameters of the characterization methods were adjusted for the particular material. Automatic systems for 4-point probe resistivity tests and Hall effect measurements were built in house and used for the characterization. The dopant segregation in all crystals grown on Earth indicates strong convective mixing and fits the full mixing profiles.