Optical properties of Ag(AlxGa1-x)S-2 epitaxial layers grown on GaAs(100) by multisource evaporation

Reflectance anomaly and photoluminescence emission spectra of Ag(AlxGa1-x)S -2 epitaxial layers, which were grown in the range of x < 0.3 on GaAs (100) substrate by the multisource evaporation method, were observed in the exci ton region. According to analyses of the reflectance anomaly spectra, assum ing the single Lorentzian oscillator model for the free exciton, it was fou nd that the oscillator energy and the damping constant of the model increas ed with an increase of x. Because the oscillator energy and the damping con stant coincided with the peak energy and the spectral full-width at half ma ximum of the emission respectively, the emission was identified as free exc iton emission, indicating the good optical quality of the layers. Taking ac count of the lattice strain effect, the composition dependence of the A(1)- mode Raman scattering frequency of the layers coincided with that of the bu lk crystals.