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