Angular dispersion of ‘‘backward’’ Raman scattering: Absorbing III-V semiconductors (GaAs)

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Abstract
A previously developed model for the angular dispersion of Raman scattering power from the surface of absorbing centrosymmetric cubic materials is extended to absorbing materials of the zinc blende type. Independent expressions have been obtained which give the scattered power due to the longitudinal and transverse long-wavelength optical phonons as a function of external scattering geometry parameters; from these calculations, it has been found that the ratio of the scattered powers shows significant dependence on the angles of incidence and detection. These results provide a quantitative method in assessing the effects of choosing an approximate rather than the exact backward scattering geometry. Experimental results obtained from GaAs are in very good agreement with the predictions of the model. Examples of physical situations are given where angular dispersion corrections become necessary.