Pseudomorphic Si1−<i>x</i>Sn<i>x</i> alloy films grown by molecular beam epitaxy on Si

Abstract

Strained Si1−xSnx (0.001≤x≤0.052) alloys were synthesized on (001) Si substrates by molecular beam epitaxy at 220 and 280 °C. The as-grown alloys were found to be pseudomorphic to Si with no indication of extended defects and tin precipitates. Within the accuracy of our studies the compressive strain in the alloys corresponds to that deduced from Vegard’s linear interpolation between the lattice parameters of Si and α-Sn. The annealing experiments show that the alloys are thermally unstable at a higher temperature (1000 °C) and that the transition of the Si1−xSnx/Si system to a lower energy state occurs through two channels: (i) alloy decomposition through precipitation of tin atoms into metallic β-Sn, and (ii) introduction of 60° misfit dislocations.