Observation of plasmons coupled with optical phonons in <i>n</i>-Al<i>x</i>Ga1−<i>x</i>As by Raman scattering

Abstract

Raman scattering from Si-doped n-AlxGa1−xAs (x=0.25) grown by molecular beam epitaxy has been studied at room temperature. In addition to the optical phonon lines, three new Raman lines have been clearly observed in samples with high carrier concentrations (n≳1×1018 cm−3). These lines are identified as the coupled plasmon-longitudinal optical (LO) phonon modes because their frequencies and relative intensities to the LO phonon lines depend on the excitation wavelength.