Analysis of the single-particle scattering spectra for spin-density fluctuations of electrons in n-GaAs at T=300 K

The line shapes of single-particle scattering spectra for spin-density fluctuations of electrons in n-GaAs with carrier concentrations ranging from 5×10¹⁵ to 7×10¹⁷ cm^-3 have been analyzed. We have found that the Raman line shapes can be very well explained by a theory developed by Hamilton and McWhorter which takes into account both the band-structure effects in semiconductors and the effects of carrier collision in a relaxation time approximation. For carrier concentration n≥2×10 ¹⁶ cm^-3, the effects of finite collision time has been demonstrated to be very important and these effects must be properly taken into account in order to satisfactorily interpret the line shapes of single-particle scattering spectra for spin-density fluctuations in n-GaAs at T=300 K. We show that although Lindhard-Mermin's expression for dielectric constant as well as Hamilton and McWhorter's theory fit the Raman line shapes equally well for carrier density n=7×10¹⁷ cm^-3, neglect of band-structure effects of the former tends to underestimate the carrier collision time. An interpretation of the deduced collision time in terms of electron-electron, electron-impurity, and electron-phonon scattering is also given.