We developed ultra-violet field-emission devices using rare-earth nitrides of Al 1-xGd xN grown by a reactive radio-frequency magnetron sputtering technique. The Al 1-xGd xN phosphor film excited by high-energy electrons shows a resolution limited, narrow intra-orbital luminescence from Gd 3+ ions at 318 nm. The devise characteristics depend on injected current and acceleration voltage, which were analyzed by considering multiple excitation process of injected high-energy electrons. © 2011 Materials Research Society.