Amorphization of Si (100) under O+ implantation studied by spectroscopic ellipsometry

The amorphization of crystalline Si (100) under 125 keV O+ ion implantation is investigated in the fluence range 1×1014 ions/cm2 to 1×1016 ions/cm2. The microstructure of the O+ implanted Si is modeled from ellipsometric data using a two phase, multilayer model within Bruggeman effective medium approximation (BEMA). The transition from the crystalline to the amorphous phase is found to be smooth and progressive. From a detailed analysis of the moments of the dielectric spectra and laser Raman spectroscopy, we infer that the amorphization occurs through a progressive disruption of long-range order caused by the overlap of amorphous nanozones. The dielectric spectrum of the fully amorphous phase is characterized using the Forouhi-Bloomer interband model.