Study of asymmetric broadening of Raman scattering in In/sub x/Ga/sub 1-x/As/InP and In/sub x/Ga/sub 1-x/As/GaAs epilayers

Abstract

Raman scattering of In/sub x/Ga/sub 1-x/As epitaxial layers on InP and GaAs substrates have been investigated with a wide range of composition. It is found that the asymmetric broadening of LO phonon modes varies with composition as well as substrate. With the one-parameter spatial correlation model, the Raman lineshapes have been analyzed, but the fits showed some deviation to the experiments. Comparing the Raman spectra with the measurements of double-crystal X-ray diffraction (DXRD), we found that, besides the alloy disorder, the Raman lineshapes are also influenced by the structural dislocation. Our results provide a framework for the use of the two-parameter spatial correlation model in the study of the Raman spectra in epilayer structures.<>