Crystalline-to-amorphous transition for Si-ion irradiation of Si(100)

Silicon (100) crystals are implanted with 1-MeV ${\mathrm{Si}}^{2+}$ ions to a fixed fluence of 1\ifmmode\times\else\texttimes\fi{}${10}^{15}$ ions/${\mathrm{cm}}^{2}$ at systematically different incident-ion dose rates, R, and substrate temperatures, T. A critical dependence on T is found for ${\mathit{R}}_{\mathit{t}}$, the critical flux for formation of a continuous amorphous layer in the substrate material. The activation energy characterizing the process is found to be 0.9\ifmmode\pm\else\textpm\fi{}0.05 eV, which is attributed to the collapse of defect complexes formed during irradiation. Critical temperatures for this process, at each fixed dose rate, are all near room temperature.