In this study, a two-step growth method with a thin predeposited indium (In) layer is reported to grow high-quality indium nitride (InN) films on silicon (Si) substrates by metal-organic chemical vapor deposition. The surface morphologies of the InN films exhibited good surface quality as determined by scanning electron microscope and atomic force microscope. The wurtizite structure with lattice constants c=5.69 angstrom and a=3.44 angstrom of the InN films was observed by high-resolution transmission electron microscopy. A 540 arc see full width at half maximum of InN(0002) diffraction peak and a 0.756 eV room-temperature interband transition energy of the InN films were also observed from x-ray diffraction and photoluminescence spectroscopy, respectively. A small temperature coefficient of -0.036 meV/K for the band gap of InN was determined. Such a small value could be explained by the small lattice mismatch and thermal expansion of InN on the Si substrate. (c) 2007 American Vacuum Society.