The effects of GaNAsSb intermediate barriers on quinary GaInNAsSb quantum well (QW) grown by molecular beam epitaxy on GaAs substrate were investigated. Series of samples grown with different Sb flux were realized to evaluate the effects. It was demonstrated that introducing GaNAsSb intermediate barriers allowed to increase QW emission. The increase of emission depends on the Sb flux. The presence of GaNAsSb layers degrades slightly the QW optical properties, but it does not degrade the QW structure and crystal quality. By using GaNAsSb barriers, a GaInNAsSb QW with room temperature emission up to 1.61 mum was achieved. (C) 2003 Elsevier B.V. All rights reserved.