Visible luminescence has been obtained from ensembles of defect‐free, InxAl(1−x)As islands of ultrasmall dimensions embedded in AlyGa(1−y)As cladding layers. These structures were grown by molecular beam epitaxy and studied with low‐temperature photoluminescence (PL) and transmission electron microscopy. Visible luminescence is produced using various compositions of InxAl(1−x)As/AlyGa(1−y)As. Quantum dot size distributions, planar densities, dot heights, and wetting layer thicknesses are presented and correlated with the PL spectra. ©1995 American Institute of Physics.