Zinc-blende GaN quantum dots were grown on 3C-AlN(0 0 1) by a vapor-liquid-solid process in a molecular beam epitaxy system. We were able to control the density of the quantum dots in a range of 5 x 10(8)-5 X 10(12) cm(-2). Photoluminescence spectroscopy confirmed the optical activity of the GaN quantum dots in a range of 10(11)-5 x 10(12) cm(-2). The data obtained give an insight to the condensation mechanism of the vapor-liquid-solid process in general, because the GaN quantum dots condense in metastable zinc-blende crystal structure supplied by the substrate, and not in the wurtzite crystal structure expected from free condensation in the droplet. (C) 2010 Elsevier B.V. All rights reserved.