(Invited) Growth and Optical Properties of Ge1-xSnx Alloy Thin Films with a High Sn Content

We have investigated the epitaxial growth of Ge1-xSnx layers with a high Sn content over 10% and their optical properties. We examined the growth of Ge1-xSnx epitaxial layers with Sn contents over 10% on Ge and InP substrates. We have achieved the epitaxial growth of a Ge1-xSnx layer with a 27%-Sn content which is much higher than a thermoequilibrium solid solubility of Sn in Ge. We have also revealed the Sn content dependence of the direct energy bandgap for Ge1-xSnx layers with wide Sn contents ranging from 5% to 27%.