Anisotropy of the thermal expansion of the Ni(Si1−xGex) phases investigated by high-temperature x-ray diffraction

Thin films of Ni(Si1−xGex) are of interest for their applications in metal-oxide semiconductor transistors as contacts and interconnections. In this work, the lattice parameters and the coefficients of linear thermal expansion (γa, γb, and γc) of the orthorhombic Ni(Si1−xGex) alloys, with 0⩽x⩽1, were determined from high-temperature x-ray diffraction data (298–1073K). A negative thermal expansion along the b axis of Ni(Si1−xGex) is observed for all x values of the Ge concentration: the magnitude of the thermal expansion coefficient decreases with increasing Ge concentration. The anisotropy of the thermal expansion is potentially important for the integration of Ni(Si1−xGex) in microelectronic devices.