Small angle grain boundary Ge films on biaxial CaF2/glass substrate

We demonstrated that it is possible to grow single crystal-like Ge films on a glass substrate using a biaxially textured CaF2 buffer layer at a low temperature of ∼400 °C. The CaF2 buffer layer with the (1 1 1)<1 2 1> biaxial orientation was grown by the oblique angle deposition technique and characterized by X-ray pole figure analysis. Transmission electron microscopy revealed that the Ge(1 1 1) heteroepitaxial films possess a single crystal-like structure with small angle grain boundaries of ≤2° misorientation.