SHI irradiation fluence and energyloss dependence effects on Ge NCs with different initial sizes embedded in SiO2

Ge nanocrystals embedded in SiO2 have been synthesized by Rapid Thermal Annealing of co-deposited Ge and SiO2 samples using RF magnetron sputtering. The dense ionization effects on thus synthesized Ge NCs with ion beam bombardment leading to modification of Ge NCs have been investigated by X-ray diffraction, Raman spectroscopy and Transmission Electron Microscopy. The effects on these embedded Ge NCs at various irradiation fluences were observed directly from the TEM analysis, complemented with X-ray diffraction and Raman spectroscopy studies. The changes in size of Ge NCs and shift in Raman spectra of Ge–Ge optical phonon vibrational mode at 300 cm−1 towards lower wavenumber side are explained as to how an embedded nanocrystal in molten state gets modified for a given electronic energy loss deposition.