Investigation of semiconductors with defects using Raman scattering

The influence of defects and carriers on lattice dynamics, especially on Raman scattering from semiconductors and metals, is considered; a comparison of the theory with experimental data is made. Phonon scattering by point, line, and plane defects produces a phonon shift and phonon broadening, which influence the Raman line shape. This effect is used for investigating strain at interfaces and for characterizing semiconductor devices. Phonon interaction with carriers involves a Coulomb field excited by optical-phonon vibrations. Our treatment of the electron–phonon interaction is based on the Born–Oppenheimer adiabatic approximation. The effect of carriers is essential near the edge of the $\omega$–$k$ region where Landau damping appears due to the electron–hole excitation. A possibility to determine the electron–phonon coupling constant from experiments with the phonon–plasmon coupled modes is discussed.