Raman Scattering in GaSe

Abstract
Raman spectra have been obtained from both the ε and γ polytypes of GaSe. The frequencies of the phonons at the zone center have been obtained for both compounds at 80 K and at 295 K. All modes have been assigned on the basis of their observed polarization dependence to an irreducible representation of the appropriate point group. A comparison of the spectra of the two polytypes has provided further confirmation of previous identifications of the various modes in ε-GaSe. Excellent agreement has been obtained between the observed and predicted dependence of the polar mode frequencies with phonon propagation direction. No evidence of conjugate modes has been observed in any of the GaSe spectra.