Absorption Spectra and Photoluminescent Processes of AlAs/GaAs Disordered Superlattices

The disordered superlattice, an artificially constructed material recently proposed, is fabricated. Photoluminescence and absorption properties of AlAs/GaAs disordered superlattices are compared with those of Al 0.5 Ga 0.5 As bulk alloy and (AlAs) 2 (GaAs) 2 ordered superlattice. Their macroscopic AlAs compositions are the same 0.5, but their microscopic structures are different. Among them, the disordered superlattice exhibits the highest photoluminescent intensity in the temperature range from 4.2 K to 300 K. Absorption spectra of three different structured materials are measured, and tail states are observed in the disordered superlattice. Strong photoluminescent capability of the disordered superlattice is interpreted in terms of the tail states created by disordering in the atomic arrangement.