Annealing temperature dependence on nickel-germanium solid-state reaction

The solid-state reaction of nickel and germanium was performed by isochronous vacuum annealing at temperatures ranging from 250 to 600 degrees C. The reaction starts at 250 degrees C to form poly-crystalline Ni-monogermanide (NiGe), and it substantially occurs at 350 degrees C. The NiGe surface roughness, as well as the NiGe grain size, increases with increasing the annealing temperature from 400 to 600 degrees C. All nickel germanide/n-Ge Schottky contacts has a similar Schottky barrier height around 0.47-0.48eV due to the Fermi level pinning effect.