The variation of the strain and structural properties of InN layers grown by molecular beam epitaxy on AlN/Si(1 1 1) substrates were investigated using reflection high-energy electron diffraction (RHEED), atomic force microscopy, scanning electron microscopy, photoluminescence, and X-ray diffraction. The RHEED intensity, the thickness of the InN wetting layer, and the lattice constant of the InN during its initial growth stage were found to be most dependent on the indium flux. Although when using a high indium flux and high growth temperature, growth would be expected to follow the Volmer-Weber growth mode during the early growth stages, in the case of the nitrogen-rich conditions, the initial InN layer grows according to the Stranski-Krastanov mode. The emission peaks are present at 0.83 eV (1500 nm) and 0.79 eV (1569 nm) for the samples made using low and high indium fluxes, respectively. These results provide important information about single-crystal hexagonal InN. (C) 2008 Elsevier B.V. All rights reserved.