A RESONANT RAMAN-STUDY ON PHONONS IN GAINAS ALINAS MULTIPLE-QUANTUM WELLS/

The LO phonon modes in the barrier layers of a GaInAs/AlInAs multiple quantum well structure are investigated by resonance Raman scattering (RRS), the excitation laser photon energy tuned to resonate with the a bove barrier interband transition energy. The resonance enhancement of LO phonon peaks are shown to be caused by Frohlich electron-phonon in teraction. The pressure-dependent profiles for both AlAs-like (LO(2) m ode) and InAs-like (LO(1) mode) Raman peak intensities are well fitted by the Gaussian lineshape. The shift between these two profiles can b e explained by the outgoing RRS mechanism, providing information on th e pressure-induced shift of the excitonic transition energy. The ampli tude ratios of the two profiles are close to 1, showing a well defined two-mode behavior and the nearly equal polarizability for Al-As and I n-As bonds in AlInAs alloy.