Data are presented on the dependence of Al content on the formation of InAlGaAs quantum dots grown by strained-layer molecular beam epitaxy. Atomic force microscopy and reflection high-energy electron diffraction patterns show that the addition of Al both slows the formation of the quantum dots in the brief time following layer deposition, and results in smaller dots of higher density. The effects might be qualitatively explained by reduced surface migration of the column III atoms due to the stronger Al bond strength. ©1997 American Institute of Physics.