Resonant Raman scattering in ion-beam-synthesized Mg2Si in a silicon matrix

Resonant Raman scattering by ion beam synthesized in silicon matrix Mg2Si phase is studied. The samples are prepared with the implantation of Mg ions with dose 4 1017 cm−2 and with two different energies 40 and 60 keV into 100 Si substrates. The far infrared spectra are used as criteria for the formation of the Mg2Si phase. The Raman spectra are excited with different lines of Ar+ laser, with energies of the lines lying in the interval from 2.40 to 2.75 eV. The resonant scattering can be investigated using these laser lines, as far as according to the Mg2Si 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 F2g 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 Mg2Si 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 Mg2Si phase is present in the form of a surface layer in the sample, prepared with implantation energy 40 keV and as low-dimensional precipitates, embedded in the silicon matrix, in the sample, prepared with the higher implantation energy.