Influence of the pre-treatment anneal on Co–germanide Schottky contacts

A thin cobalt layer is deposited by electron beam evaporation onto a germanium substrate after an in situ cleaning annealing at 400 or 700 °C. The effect of these pre-treatments on the Co/Ge Schottky barrier properties and on the germanide formation is investigated by using different techniques. A strong influence of the pre-treatment is observed. The pre-treatment at 700 °C removes the native oxide but enhances the diffusion of contaminants. After post-metal deposition annealing, the sample pre-treated at 700 °C shows a double layer structure due to interdiffusion, whereas some large isolated islands are present in the sample pre-treated at 400 °C.