Raman Scattering by Silicon and Germanium

Raman scattering from single-crystal Si and Ge at 300\ifmmode^\circ\else\textdegree\fi{}K was measured using an argon laser as the exciting source. The first-order Raman spectrum yields energies for the $k\ensuremath{\approx}0$ optical modes of 520.2\ifmmode\pm\else\textpm\fi{}0.5 ${\mathrm{cm}}^{\ensuremath{-}1}$ for Si and 300.7\ifmmode\pm\else\textpm\fi{}0.5 ${\mathrm{cm}}^{\ensuremath{-}1}$ for Ge. These values are in reasonable agreement with other determinations. The full widths at half-intensity were found to be 4.6 ${\mathrm{cm}}^{\ensuremath{-}1}$ for Si and 5.3 ${\mathrm{cm}}^{\ensuremath{-}1}$ for Ge. These values are compared with theoretical predictions. A Raman band was observed in Si at 950 ${\mathrm{cm}}^{\ensuremath{-}1}$ which is attributed to second-order scattering and is compared with theoretical predictions.