The raman properties of semiconductor compounds

In this work, Raman scattering by longitudinal optical phonons in In1-x-yGaxAlyAs quaternary alloys lattice-matched to InP(with x+y » 47%) wasinvestigated. The quaternary alloy samples were grown as epilayers on (001)InP substrates by molecular beam epitaxy. The Raman phonon spectra show athree-mode behaviour involving the InAs-, GaAs- and AlAs-like longitudinaloptic phonon modes. The frequencies of GaAs and AlAs-like modes varylinearly with the concentration of the Ga (or Al) while the position of the InAs-like phonon remains nearly constant. We show that the ratio of intensities of themodes is proportional to the corresponding ratio of their compositions. Theasymmetric broadening in the Raman line shapes of the LO phonon mode dueto the disorder-activations can adequately be explained by a spatial correlationapproach.Science Code : 4040501Key Words : Quaternary, phonon modes, Raman spectra, RCI modelPage Number : 51Adviser : Asist. Prof. Dr. M. Mahir BÜLBÜL