Uniform InAs quantum dots (QDs) were closely stacked on self-formed GaAs nanoholes by molecular beam epitaxy (MBE) using Stranski-Krastanov (SK) growth mode. GaAs nanoholes were spontaneously formed just above the embedded TnAs QDs by thermal annealing. Since surface migration length of In adatoms is longer than a spatial distance between neighboring nanoholes, InAs islands were randomly formed on the nanoholes. As InAs coverage increased, uniformity of the stacked InAs QDs improved by a size-limiting effect due to {1 3 6} facet formation. The closely stacked InAs QDs with uniform size were strongly coupled with underlying InAs QDs through the nanoholes and revealed extremely narrow photoluminescence (PL) spectra with about 15 meV in linewidth. (c) 2006 Elsevier B.V. All rights reserved.