Sn-inserted Al-induced layer exchange for large-grained GeSn thin films on insulator

Large-grained polycrystalline GeSn layers on glass are achieved through the layer exchange between a-Ge and Sn-doped Al layers. The thicker Sn layers, inserted below Al layers, provided the faster growth velocity, resulting in the smaller grain size of the GeSn layer. Controlling the Sn thickness (10 nm) and the growth temperature (300 °C) allowed for approximately 80% (111)-oriented GeSn layer with grains having an average size of 40 μm. The lower growth temperature led to the higher Sn content in GeSn: 300 °C resulted in a Sn content of 2%. These findings are meaningful to researches related to GeSn on insulators for fabricating advanced electrical and optical devices on inexpensive substrates as well as on Si platforms.