PHOTOLUMINESCENT PROPERTIES AND OPTICAL-ABSORPTION OF ALAS/GAAS DISORDERED SUPERLATTICES

A disordered superlattice, a recently proposed artificially constructed material, is fabricated and photoluminescent properties and optical absorption are investigated. Disorder is intentionally introduced into the period of the superlattice in order to enhance its photoluminescence. The photoluminescent temperature dependences and the optical absorption spectra of Al 0.5Ga0.5As bulk alloy, AlAs/GaAs ordered superlattice, and AlAs/GaAs disordered superlattice are studied and compared. The optical absorption spectra suggest that localized states are created in the band tail of the AlAs/GaAs disordered superlattice. The photoluminescence spectra of the disordered superlattice are strongly dependent on the localized states, and the temperature dependence of photoluminescence intensities obeys the same relation IPL∝[1+A exp(T/T0)]-1 as that reported for amorphous semiconductors.