The InGaAsN films lattice-matched to Ge substrates and having an about 1 eV bandgap energy have been grown on Ge(001) vicinal substrates by metal organic vapor phase epitaxy (MOVPE) varying the group-V precursor flow rates, and their photoluminescence (PL) properties have been investigated. Rapid thermal annealing (RTA) with suitable conditions has improved the luminescence properties. The PL spectral shifts with temperature and excitation intensity indicate that a larger flow of the group-V precursors enhances the carrier localization due to the potential fluctuations caused by the compositional non-uniformity and other localized states which originate from impurities or crystal defects. The huge amount of 1, 1-dimethylhydrazine (DMHy), which can efficiently incorporate N, may also introduce a significant amount of carbon species which can act as impurities, or may suppress the surface migration of the group-III atoms resulting in compositional non-uniformity and crystal defects. (C) 2012 Elsevier B.V. All rights reserved.