The Brillouin, Raman and Infra-Red Spectra of Gallium Phosphide

Abstract

The first purpose of this talk is to describe digital techniques used in our laboratory to obtain Brillouin spectra by Fabry-Perot interferometry. We have also used some of these techniques in Raman spectroscopy and this work will also be discussed. The spectra we have chosen to show are of GaP since we have also obtained high-resolution, infra-red two-phonon absorption bands for this material. A preliminary attempt at a shell-model calculation of the lattice-vibration bands has been made using the elastic constants found from the Brillouin spectra and compared with the second-order Raman and infra-red data. Structure near the central laser peak in the Raman spectrum has been found, which has not yet been explained. This extends to about 100 cm^-1 and has two components.