We investigated the growth of QDs on AlGaAs/GaAs(3 1 1)B by atomic hydrogen assisted molecular beam epitaxy. In the growth of QDs directly on AlGaAs, the QDs size fluctuation increased with increasing Al composition of the AlGaAs underlying layer. However, the uniformity of QDs size and the ordering were improved by introduction of a thin GaAs spacer layer. It was concluded that there is a strong interaction between the InGaAs-strained and underlying layers. The strong photoluminescence intensity of QDs confined in AlGaAs with GaAs spacer layers was maintained up to room temperature. Hence, the carrier collection efficiency into the QDs was improved and the escape of carriers from the QDs was suppressed by introducing higher potential AlGaAs barrier layers.