The quinary T]GaInNAs-based double quantum well (DQW) structures were grown on GaAs substrates by electron cyclotron resonance (ECR)-MBE and the samples were probed by secondary ion mass spectroscopy (SIMS). Light emitting diodes (LEDs) were fabricated using these DQW wafers and their electroluminescence (EL) behaviors were studied at different temperatures. The effects of different barrier layers and substrate orientations on the amount of Tl incorporation and on the temperature dependency of the EL peak wavelengths of the LEDs were studied. Higher incorporation of Tl into the quantum well (QW) region and the ensuing change in the temperature dependency of the peak wavelengths owing to the TlGaAs barrier layer are reported. GaAs substrates having (3 1 l)B orientation were found to allow more Tl incorporation as compared to (10 0) and (3 1 I)A oriented substrates. The LEDs fabricated out of the TlGaInNAs/TlGaAs/(3 1 1)B GaAs DQW structures showed the least temperature dependency of the EL peak wavelengths exemplifying the usefulness of Tl in the QW as well as barrier region. (c) 2006 Elsevier B.V. All rights reserved.