LIGHT-SCATTERING BY ELECTRONS IN THE EXCITONIC ABSORPTION REGION OF GAAS

A study has been made of the effect of the additional generation of ph otoexcited electrons on the excitonic absorption and luminescence spec tra of ultrapure GaAs samples at T = 2 K. The observed increase in the absorption coefficient for the ground (n = 1) excitonic state is show n to originate from the polariton character of the energy spectrum of this state and to be due to an increase of polariton damping. The incr eased damping observed under electron generation is caused by polarito n scattering from hot electrons as the latter undergo thermalization. As a result, the polaritons are heated. The changes observed in the lu minescence spectra are produced by the reverse effect of electron heat ing and polariton cooling. (C) 1997 American Institute of Physics.