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Raman study of longitudinal optical phonon-plasmon coupling and disorder effects in heavily Be-doped GaAs

1991; American Institute of Physics; Volume: 69; Issue: 7 Linguagem: Inglês

10.1063/1.348957

1520-8850

Adnen Mlayah, R. Carles, G. Landa, E. Bedel, A. Muñoz-Yagüe,

Semiconductor materials and devices

Raman spectroscopy measurements have been performed on GaAs:Be samples with high crystalline quality and exceptional heavy doping level ranging from 1019 to 1.4×1021 cm−3. The recorded spectra show a structure we assigned to a coupled LO phonon-damped plasmon mode. A theoretical expression for the Raman scattering rate by this mode has been derived from a dielectric model and compared to the experimental data. Using a fitting procedure the doping level of the samples has been estimated in agreement with Hall measurements. Moreover, the study of the Raman intensity evolution of both unscreened-LO and coupled phonon-plasmon structures, provided a convenient and rapid method to determine the activated carrier density in p-doped polar semiconductors. Disorder effects due to the dopant impurities have been also observed and analyzed using a spatial correlation model description.