Resonance Raman scattering studies of composition-modulated GaP/InP short-period superlattices

Resonance Raman scattering and electroreflection measurements on laterally composition modulated GaP/InP short-period superlattices are presented. The electroreflectance spectra give the fundamental band-gap energy of the lat eral superlattice at 1.69+/-0.05 eV, which is about 210 meV lower than the band-gap energy of a GaInP random alloy with the same overall composition. In resonance Raman spectra measured with the polarization of both excitatio n and scattered photons along the composition modulation direction, the GaP -like longitudinal optical phonon redshifts by 4.0+/-0.5 cm(-1) near the re sonance with the fundamental energy gap. A comparison of the experimental d ata with a model calculation gives the average In composition in the In-ric h region as 0.70+/-0.02, and the average Ga composition in the Ga-rich regi on as 0.68+/-0.02. [S0163-1829(99)04531-2].