Orientation dependence of the stability of strained Sn epilayers grown on Cd0.8Zn0.2Te substrates

This paper reports on the strain energy density in epitaxial overlayers that depends on the substrate's surface orientation. The affect of a growth orientation strain energy contribution to the phase stability was studied by growing overlayers of metastable, semiconducting α-Sn films on the (100) and (111) surfaces of Cd0.8Zn0.2 Te substrates. On the (100) surface, the α-phase of Sn remains stable for coverages up to an beyond 125 ML. On the (111) surface though, the Sn overlayer shows metallic behavior from a partial α → β phase separation for coverages lower than 100 ML. Static calculations using the stress-strain relationship bear out these experimental results by showing that the strain energy density for the (111) growth direction is 38% larger than for the (100) direction