Properties of Sn/Ge superlattices

Short-period strained-layer alpha -Sn/Ge superlattices have been synthesized recently by a low temperature molecular beam epitaxy technique which allows a large variation of substrate temperature. Thin, tetragonally distorted alpha Sn layers h ave been stabilized on Ge substrates by growth conditions far way from thermal equilibrium. The fundamental bandgap of Sn/Ge superlattices is shifted towards lower energies with increasing average Sn concentration, as expected from theory.