Future Air Force RF links will require the speed, cost, reliability, weight, and EMI-immunity advantages of a monolithically integrated optical-electronic technology. GaAsN is a direct band-gap compound semiconductor material which potentially can be lattice-matched to silicon. This would permit true monolithically integrated optical-electronic circuits to be fabricated. To date, films of GaAsN grown by MBE under most conditions exhibit segregation into coexisting GaAsN, GaN and GaAs phases. The composition, microstructure, and signatures of these films in X-ray diffraction, Auger, and TEM analyses are reported. The possible ordering of these films is analyzed.