Thermal stability of highly compressive strained germanium-tin (GeSn) grown by molecular beam epitaxy

Highly strained Ge
_1-x
Sn
_x
films were epitaxially grown on Ge(001), with x up to 0.17. Good crystalline quality and a relatively flat surface were obtained. Critical temperatures exist for Sn segregation for various x. XPS shows that the Sn surface segregation could occur at temperatures as low as 400 °C for Ge
_0.932
Sn
_0.068
.