Raman scattering determination of free charge density using a modified hydrodynamical model

We have carried out a systematic evaluation of the accuracy of the charge d ensity Values obtained by fitting a modified hydrodynamical model to Raman spectra. The hydrodynamical model has been extended to provide a more accur ate evaluation of wave vector dependence, conduction band nonparabolicity a nd free carrier thermal distribution effects through an energy dependent ef fective mass, so that it can be applied to a wide range of carrier densitie s. We have used this extended model to fit the coupled-mode Raman spectra o btained from a series of n-InP samples with electron densities in the 10(17 )-10(19) cm(-3) range, and the carrier density values obtained follow close ly the results of the more elaborate Lindhard-Mermin model over the whole d ensity range.