Room-temperature study of cobalt metal growth on Ge(111)

Abstract

The room-temperature growth of Co on Ge(111) has been studied by MeV ion channeling and Auger electron spectroscopy in an ultrahigh vacuum environment. It has been found that even at room temperature, Co reacts with the Ge substrate and effectively displaces ∼3 monolayers of Ge atoms from their original lattice positions forming a possible interfacial layer of CoGe. Further deposition of Co resulted in a continuous and uniform metal overlayer. These room-temperature results are very similar to those found for Co on Si(111). After annealing a sample of 35 Å of Co on Ge at 600 °C for 1 h, ion channeling and transmission electron microscopy data showed the annealed film to consist of small crystalline islands with a stoichiometry of Co5Ge7. The similarities and differences between Co on Ge and Co on Si are also discussed.