SEM Study of Phase Transformation in alpha-Sn Thin Films.

The nucleation of beta-Sn (tetragonal structure) from alpha- Sn (diamond structure) has been studied. The alpha-Sn was grown by molecular beam epitaxy on InSb and has specular morphology and good crystallinity. The growth stages were characterized in situ using RHEED and after growth in the scanning electron microscope and by optical microscopy. Heating experiments were also performed. Beta-Sn in both the as grown and thermally transformed films has a morphology that is characteristic of martensitic phase transformations. A model for the transformation that details the lattice correspondence between the alpha and beta structures is given.