Raman scattering is used to investigate p-type accumulation zones on t
he substrate side of ZnSe-GaAs heterostructures. The intensity imbalan
ce between (i) the near-interfacial phonon-plasmon coupled mode locate
d below the TO frequency and (ii) the uncoupled LO mode from the deep
substrate, is studied at a single wavelength under increasing illumina
tion. Competition between electric field-induced scattering and more t
rivial scattering volume effects is discussed. (C) 1998 Elsevier Scien
ce B.V. All rights reserved.