Homoepitaxial gallium nitride based photodetector and method of producing

1-x-yxy1-z-w zw1-xx5 −2A photodetector comprising a gallium nitride substrate, at least one active layer disposed on the substrate, and a conductive contact structure affixed to the active layer and, in some embodiments, the substrate. The invention includes photodetectors having metal-semiconductor-metal structures, P-i-N structures, and Schottky-barrier structures. The active layers may comprise GaAlInNPAs, or, preferably, GaAlN. The gallium nitride substrate comprises a single crystal gallium nitride wafer and has a dislocation density of less than about 10cm. A method of making the photodetector is also disclosed.