Raman scattering in InP1-xAsxalloys

Abstract
Phonons in the alloy system InP1-xAsx have been studied by Raman spectroscopy. Long-wavelength optical phonons display a two-mode behaviour throughout the whole composition range. The frequencies of the local and gap modes found experimentally at 77K are given. Short-wavelength phonons proceed from second-order processes near x=0 and 1 and from first-order disorder-induced scattering around x=0.5. This latter mechanism explains the two features around 55 cm-1 and 145 cm-1. They are attributed to the maxima of the density of transverse and longitudinal acoustic bands.