Investigation Of Carrier Localization In Inas/Alsb Type-Ii Superlattice Material System

We investigate carrier localization in the InAs/AlSb type-II superlattice (T2SL) material system using temperature- and excitation power (I-ex)-dependent photoluminescence (PL). Evidence of carrier localization in T2SLs was observed by an S-shaped temperature dependence of the PL peak position. Analysis of the I-ex-dependent PL at various temperatures also shows the existence of carrier localization in the T2SLs. The thermal activation energies in T2SLs were extracted to identify the nonradiative recombination mechanisms and the possible origins of localized states. We found that there are two thermal activation energies, E-1 = 8.2-1.2 meV and E-2 = similar to 60 meV at various I-ex. We interpret E-1 as a thermal activation energy that comes from Anderson localization, associated with roughness due to As-2 diffusion into the interfaces. This is because the extracted E-1 values are comparable to the exciton binding energy of localization in various quantum structures. Carrier trapping at a state in the InSb interfacial layer (Tamm state) may account for the origin of E-2. Based on previous reports, we believe that the 60 meV state might be a Tamm state if we consider thickness variations in the InSb interfacial layer for the T2SLs. Published under license by AIP Publishing.