Low temperature epitaxial growth of Ge on CaF ₂ buffered cube-textured Ni

Quasi-single crystal Ge films were grown on cube textured Ni substrate at a temperature of 350 °C using an insulating buffer layer of CaF ₂. A direct deposition of Ge on Ni at 350 °C was shown to alloy with Ni. From x-ray pole figure analysis, it was shown that Ge grew epitaxially with the same orientation as CaF ₂ and the dispersions in the out-of-plane and in-plane directions were found to be 1.7±0.1° and 6±1°, respectively. In the out-of-plane direction, Ge[111]||CaF ₂[111] ||Ni[001]. In addition, the Ge consisted of four equivalent in-plane oriented domains such that two mutually orthogonal directions: Ge〈211〉 and Ge〈011〉 are parallel to mutually orthogonal directions: Ni〈110〉 and Ni〈110〉, respectively, of the Ni(001) surface. This was shown to originate from the four equivalent in-plane oriented domains of CaF ₂ created to minimize the mismatch strain between CaF ₂ and Ni in those directions.