Interface plasmon-phonons modes in ion-beam synthesized Mg2Si nanolayers

Raman scattering of samples, representing n- and p-type Si matrix with unburied Mg2Si nanolayers, formed by ion-beam synthesis, are studied. Despite the features in the Raman spectra attributed to the polariton modes with frequencies between those of the TO and LO phonons, additional features outside this interval are detected. The frequencies of these features are very sensitive to the plasma frequency, being different in the n- and p-type Si matrix and to the annealing time. The latter implies the generation of interface plasmonphonons modes. The frequencies of the interface plasmon-phonon modes are calculated and compared with the experimental results. The order of the carrier concentration in Mg2Si, the data of which are not available in the literature, is evaluated. (authors)