Resonant Raman scattering by ion beam synthesized in silicon matrix ${\mathrm{Mg}}_2\mathrm{Si}$ phase is studied. The samples are prepared with the implantation of ${}^{24}\mathrm{Mg}^{+}$ ions with dose $4\times {10}^{17}{\mathrm{cm}}^{-2}$ and with two different energies 40 and $60\mathrm{keV}$ into (100)Si substrates. The far infrared spectra are used as criteria for the formation of the ${\mathrm{Mg}}_2\mathrm{Si}$ phase. The Raman spectra are excited with different lines of ${\mathrm{Ar}}^{+}$ laser, with energies of the lines lying in the interval from $2.40\text{to}2.75\mathrm{eV}$. The resonant scattering can be investigated using these laser lines, as far as according to the ${\mathrm{Mg}}_2\mathrm{Si}$ band structure, there are direct gaps with energies in the same region. The energy dependences of the scattered intensities in the case of the scattering by the allowed $F_{2g}$ and the forbidden LO-type modes are experimentally obtained and theoretically interpreted. On the base of the investigation energies of the interband transitions in the ${\mathrm{Mg}}_2\mathrm{Si}$ are determined. It is found also that the resonant Raman scattering appears to be a powerful tool for characterization of a material with inclusions in it. In the particular case it is concluded that the ${\mathrm{Mg}}_2\mathrm{Si}$ phase is present in the form of a surface layer in the sample, prepared with implantation energy $40\mathrm{keV}$ and as low-dimensional precipitates, embedded in the silicon matrix, in the sample, prepared with the higher implantation energy.

• Received 6 April 2005

DOI:https://doi.org/10.1103/PhysRevB.72.115330