Unveiling the effects of Sb or Bi doping on lattice strain and Raman spectra in Mg2Si single crystals

Abstract

We thoroughly investigated the Raman peaks of Sb- or Bi-doped Mg2Si single crystals grown by the vertical Bridgman techniques and clarified the relationship between the Raman peak shift and lattice strain using first-principles calculations. Rietveld analysis of powder x-ray diffraction revealed that the lattice constant increased monotonically with Sb and Bi doping amounts. Raman spectroscopy demonstrated that the F2g mode of Mg2Si (near 258 cm−1) shifted to lower wavenumbers with increasing doping amounts. This peak shift was mainly attributed to the lattice strain, which was revealed by the first-principles calculations. These findings provide the usefulness of Raman spectroscopy for Mg2Si substrates.