Reaction of thin Ni films with Ge: Phase formation and texture

The solid-state reaction between a 30-nm-thick Ni film and Ge substrates was investigated using in situ x-ray diffraction, diffuse light scattering, and four-point probe electrical measurements. Our results reveal that Ni 5Ge 3 and NiGe appear consecutively on Ge(111) while they grow simultaneously on amorphous Ge (α-Ge) and Ge(001). Furthermore, phase formation temperatures depend strongly on the nature of the substrate being the lowest on α-Ge and the highest on Ge(111). X-ray pole figure measurements of the NiGe phase obtained from the reaction with an amorphous substrate indicate a completely random texture while several epitaxial and axiotaxial texture components are observed on both Ge(001) and Ge(111). The texturing for the NiGe film on Ge(111), which showed a sequential phase formation, is an order of magnitude more pronounced than for the film on Ge(001) which showed a simultaneous growth. © 2006 American Institute of Physics.