SECOND-ORDER RAMAN-SPECTRA AND PHONON DISPERSION IN GAP

The second-order Raman spectrum of GaP has been investigated experimentally. The experiments are performed on oriented single crystals at both 300 and 77 degree K. A critical point analysis of the data has been carried out with the aid of the polarization selection rules. The resulting frequencies are also consistent with a theoretical model which in turn is used to calculate the phonon dispersion throughout the Brillouin zone.