The dilute-nitride GaInNAs shows great promise in becoming the next choice for long-wavelength (0.9 to 1.6 μm) photodetector applications due to the ability for it to be grown lattice-matched on GaAs substrates. GaAs-based devices have several advantages over InP-based devices, such as substrate cost, convenience of processing, and optoelectronic band parameters. This paper will present results from the first high-quality thick GaInNAs films grown by solid state molecular beam epitaxy with a nitrogen plasma source and the first high efficiency photodetectors which have been fabricated from those materials. GaInNAs films up to 2 microns thick have been grown coherently on GaAs substrates. These films exhibit reasonable photoluminescence intensities at peak wavelengths of 1.22 to 1.13 μm before and after a rapid thermal anneal at a series of temperatures. PIN photodiodes with these thick GaInNAs films in the intrinsic regions show responsivity (better than 0.5 A/W at 1.064 μm), dark current (200 nA at -2 V), and signal-to-noise ratio (greater than 105) approaching those of commercially available InGaAs/InP devices. Furthermore, it will be shown that these devices show significantly lower dark current and higher signal-to-noise ratio than similar metamorphic InGaAs/GaAs structures.