Disordered superlattices

A disordered superlattice (d-SL) is a kind of disordered crystalline semiconductor in which atomic alignment is disordered in some directions but ordered in other directions. The d-SL exhibits remarkable luminescence capability caused by artificial disordering along one direction. (AlGaAs)(AlGaAs), (AlP)(GaP) and (SiGe)Si d-SLs are grown. The temperature dependence of (AlGaAs)(AlCaAs) photoluminescence (PL) is described. The disordered effect appears most strongly in the (AlAs)(GaAs) d-SL. The (AlP)(GaP) d-SL emits electroluminescence 4.5 times more strongly than the bulk alloy and the ordered sublattice. The (SiGe) Si d-SL also emits enhanced luminescence. For further improvement, increases in the band offset and in the total number of monolayers in the superlattice are required. The physical mechanism for the unusual luminescence properties of a d-SL is discussed in terms of carrier localization and confinement. A d-SL can be suggested to be a promising material for the enhancement of the luminescence capability.