Structure and stability of metastable α-Sn

We report for the first time the growth of high quality films of metastable α-Sn. The structural properties of the molecular beam epitaxy grown metastable α-Sn are investigated by means of in situ reflection high-energy electron diffraction (RHEED) analysis, scanning electron microscopy including electron channeling patterns, and high-resolution x-ray scattering techniques. Scanning electron microscopy reveals a growth morphology of smooth and uniform surfaces. RHEED patterns yield a highly streaked (2×1) surface reconstruction suggesting a layer-by-layer growth mechanism. Triple-axis x-ray diffractometry was employed to determine structural parameters and the strain distribution. In-plane rocking scans of the (400) reflection indicate a half width of 3 arcsec for the heterostructure α-Sn/InSb. Out-of-plane scans reveal a tetragonal distortion perpendicular to the film plane, contributing a net strain of ∼0.28%. These results are in quantitative agreement with values calculated using simple elastic theory.