Raman Scattering and the Two-Phonon Density of States in GaAs

Abstract

A knowledge of the vibration spectrum in GaAs is of importance for explaining a variety of phonon transport and scattering experiments. [1] Recently two-phonon Raman Scattering [2] has been used to probe the non-equilibrium phonon population of optically excited GaAs. This work has led to the most precise determination of the phonon spectrum at the critical points of GaAs. It is therefore appropriate to fit the parameters of a lattice vibration model by comparing the computed two-phonon density of states against the experimental Raman data. The comparison is presented here for both the overtones and the sum and difference frequency combinations. Although calculations have been previously presented [3] for overtones in GaAs, we are not aware of any calculations for the combinations. The latter, particularly the difference frequencies, provide the most sensitive and rigorous test of the analysis. Finally, the model can then be used to compute the one-phonon spectrum for comparison with neutron scattering results and for calculating transport properties.

Work at City College supported in part by ARO and DOE. Work at Purdue University supported in part by NSF Grant 82–17442.