Microstructural Evolution and Electrical Characteristics of Co-Germanide Contacts on Ge

The microstructural evolution and corresponding electrical contact properties of Co-germanide systems were investigated. The Co-germanide formation process underwent several intermediate, high-resistive phases (CoGe and ), while low-resistive was formed over in a narrow process window of . Because of the strong Fermi level pinning effect, Co, CoGe, and phases exhibited Schottky contact behaviors with similar Schottky barrier heights on n-type Ge and ohmic contact behavior on p-type Ge, respectively. However, for the -type Ge contact formed at , a nearly ohmic contact behavior started to appear, which was attributed to the possible diffusion of Co atoms into the Ge substrate due to the high-temperature germanidation process.