Self-assembled lnAs quantum dots (QDs), without and with an AlAs cap, were grown on (311)B GaAs substrates by molecular beam epitaxy. Surface morphologies of QDs were characterized by atomic force microscopy. Photoluminescence (PL) was performed in the 4-300 K temperature range. For QDs without AlAs cap, sharp and intense PL emitted from wetting layer was observed. PL from QDs was relatively weak at 4 K. The PL intensity of QDs decreased as measurement temperature increased and was not observed at 300 K. For QDs with AlAs cap, PL from WL vanished while PL from QDs were substantially enhanced at 300 K. Suppression of PL from WL indicates that the thickness of WL was reduced due to phase separation result from AlAs cap, which is an effective way to improve the PL of InAs QDs grown on (311)B GaAs substrate. (C) 2015 Elsevier B.V. All rights reserved.