Studying near-surface layers of germanium implanted with cobalt ions

Results of an investigation of the surface of germanium nanostructured by means of ion implantation are presented. Single-crystalline germanium ($c$-Ge) plates were irradiated by 40-keV cobalt Co$^+$ ions in a dose range of (2 – 8) $\times$ 10$^{16}$ ion/cm$^2$. Evolution of the germanium surface morphology with increasing ion dose was studied by method of scanning electron microscopy. It is established that an increase in the ion implantation dose is accompanied by gradual formation of a surface layer consisting of spherical particles with diameters of $\sim$150 nm. Analysis of the X-ray diffraction patterns of samples was indicative of the appearance of nanosized cobalt germanide (CoGe) particles in the ion-implanted surface layer.