Formation of Fe nanoclusters embedded in Ge and irradiation induced amorphisation and crystallisation of Fe+ ion implanted Ge

The 60 keV Fe+ ion-implantation in Ge〈1 1 1〉 at room temperature produced Fe nanoparticles embedded in a-Ge matrix and the a-Ge is recrystallised by beam annealing of the sample at 250 °C with 1 MeV Ge+ ions. The study of the irradiation-induced amorphization and subsequent recrystallisation by ion beam annealing in Ge was carried out using Raman scattering and grazing incidence X-ray diffraction (GIXRD) techniques. Raman scattering reveals the amorphization of Ge at a fluence of 5 × 1015 ions/cm2. With further irradiation, TO-like phonon mode evolves and the full-width at half-maximum (FWHM) of this mode increases with fluence. We have estimated the amount of bond disorder from the FWHM of TO-like mode. Upon self-ion irradiation of the Fe+ ion-implanted Ge at 250 °C, a partial crystallization of amorphous Ge is observed as evident from the reappearance of optical phonon mode. The GIXRD measurements also support the amorphization and crystallization of Ge. The presence of Fe nanoclusters was observed by using low-frequency Raman scattering (LFRS). The Fe-nanoclusters are expected to form directly in the collision cascade.