Raman scattering in some III‐VI layer single crystals

Polarized Raman spectra of InSe and InS crystals are obtained, the assignment of frequencies is given, and atomic displacements are found at all normal vibrations. In the InSe crystal, force constants of interaction of In‐Se and In‐In atomic planes are evaluated. It is shown that the Raman spectrum of InS has a doublet nature typical for layer crystals. The frequencies of rigid‐layer modes forbidden in the Raman spectrum are calculated in the InS crystal. It is found that interlayer force constants in the InS crystal are only 5 to 10 times smaller than the intralayer covalentbond force constants.