Raman scattering study of the electron-phonon coupling in GaInAs-InP quantum wells

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Abstract
Recent Raman scattering studies of Ga0.47In0.53As-InP quantum wells have shown that the form of the alloy optical phonons can be quite different from that observed in the bulk due to coupling between the phonons and the two-dimensional electron gas (2DEG). However, the limited range of samples studied so far has made the elucidation of the precise coupling mechanism difficult. The authors report here a Raman scattering study of the GaInAs optical phonons in a wide range of undoped GaInAs-InP quantum wells with well widths in the range 50-300 AA. The frequencies and intensities of the two LO phonons of the alloy are studied as a function of both well width and photoexcited carrier density and a resonant coupling between the electrons and the GaAs-like LO phonon is observed when the lowest electronic inter-subband spacing approaches the phonon energy. These results are discussed in terms of the coupling between phonons and intersubband collective excitations.