MBE成長高濃度p型GaAsの過剰減衰LOフォノン-プラズモン結合モードによるラマン散乱

概要

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Raman scattering spectra are measured for Be doped p-GaAs epitaxial films grown on the semi-insulating GaAs substrate by the Molecular Beam Epitaxy (MBE) method. The obtained spectra are analyzed by assuming the following three kind of elementary excitations : (i) Pure LO phonon mode at the surface depletion layer, (ii) the coupling mode between LO phonon and plasmon through the so-called deformation potential and electrooptic mechanism, (iii) TO phonon mode coupled with the single-particle excitation through the so-called Fano effect. The calculated spectra well represent the experimental Raman spectral profiles. In the Raman scattering by LO phonon-plasmon coupled mode for heavily doped p-GaAs, the splitting into L_+ and L_- modes is not observed due to the over damping of plasmon originated from the short relaxation time and large effective mass of the free hole.
東海大学の論文