We present a growth technique to improve the structural property of InP-based multilayer quantum-dot (QD) structures. A thin layer of AlGaInAs grown under a group-III stabilized condition can effectively smooth out the three-dimensional growth front caused by the QD formation. Thus, the AlGaInAs barrier layers with high crystal quality and smooth interfaces can be achieved. Using this technique, an InP-based QD infrared photodetector structure containing ten-period QD layers has been grown using molecular beam epitaxy, and its high structural and optical quality was confirmed by x-ray diffraction and photoluminescence measurements. (c) 2006 American Vacuum Society.