INFLUENCE OF STRUCTURAL DISORDER ON RAMAN-SCATTERING IN AMORPHOUS POROUS SILICON

The Raman scattering spectra of amorphous porous silicon are investiga ted. It is found that the so-called boson peak in the acoustical part of the Raman spectra is more sensitive to the degree of structural dis order than the optical mode, which is normally used to determine the l atter. This can be explained by the fact that the coupling coefficient of light to acoustical phonons has an additional factor in comparison with that of optical phonons: the square of inverse correlation lengt h of vibrational excitations. This means that the Raman scattering int ensity on acoustical phonons has an additional dependence on the degre e of disorder in comparison with the scattering on optical phonons.