PHOTOLUMINESCENCE AND RAMAN-SCATTERING ANALYSIS OF INXGA1-XAS EPILAYERS GROWN ON GAAS BY LOW-PRESSURE METALORGANIC CHEMICAL-VAPOR-DEPOSITION

The layer composition and strain variation in InxGa1-xAs epilayers have been examined using low-temperature photoluminescence and Raman scattering. The In concentrations determined from the Raman shift of GaAs-like longitudinal optical phonons in strain-relaxed thick epilayers agree with those obtained by double crystal X-ray diffraction. The phonon frequencies measured as a function of the layer thickness reveals a strain variation which can also be observed in the photoluminescence spectra. The critical thicknesses have been estimated from Raman scattering and photoluminescence and are consistent.