Impurity-induced resonance Raman scattering at the (e,A0) threshold in lightly carbon-doped p-type GaAs at

In lightly carbon-doped p-type GaAs the impurity-induced resonance Raman scattering (RRS) by one longitudinal-optic (LO) phonon has been studied at low temperature by using a tunable Ti–sapphire laser. In spite of involvement of strong luminescence in the spectral region of the Raman scattering, a pronounced scattering resonance at the (e,A0) threshold has been well identified. Both the extrinsic LO-Raman scattering and the luminescence of (e,A0) LO phonon replicas have been analyzed in a quantitative way. We find that carbon-acceptor-induced extrinsic scattering is fairly intense compared to the intrinsic Raman scattering. It is interpreted in terms of the large oscillator strength of the (e,A0) transition. Compared to the intrinsic scattering due to free electron–hole pairs, the large (e,A0) oscillator strength leads to about two orders of magnitude enhancement in the Raman intensity.