High-quality, thin-film, lattice-matched (LM) InAsyP1-y/InxGa1-xAs double heterostructures (DHs) have been grown lattice mismatched on InP substrates using atmospheric-pressure metalorganic vapor-phase epitaxy. The low-band gap InxGa1-xAs layers in the DHs have room-temperature band gaps that range from 0.47 to 0.6 eV. Both the optical and electronic properties of these films have been extensively measured. The band-to-band photoluminescence is quite strong and comparable to that found for LM InP/In0.53Ga0.47As DHs grown on InP. Recombination lifetime measurements of undoped DH structures show minority-carrier lifetimes in excess of 1 μs in most cases. The earlier properties make the band gap-flexible InAsyP1-y/InxGa1-xAs DH system attractive for applications in high-performance, infrared-sensitive devices. © 2001 American Institute of Physics.