Photoluminescence and photoluminescence excitation spectra of AlAs/GaAs disordered superlattices with various disordered lengths

A disordered superlattice (d-SL) is a superlattice with artificial disordering. Temperature dependence of photoluminescence (PL) and PL excitation (PLE) spectra are measured for AlAs/GaAs short-period d-SLs with various disordered lengths and are compared with those of ordered superlattices (o-SLs). X-ray satellite peaks are split and PL peak energies are red-shifted with increase of the unit length of disorder. From the PLE results, radiative recombination processes in the AlAs/GaAs d-SLs are inferred to be type-II. The d-SL with a longer unit length of disorder shows more complicated variations in the PL spectrum with changing temperature. The variations are intensified with increase of the disorder lengths. These variations indicate that the localized strength which corresponds to the disorder length is different among the states induced by disordering. The dominant radiative recombination states at higher temperature would correspond to stronger localized states in the d-SLs.