Multiple excitation process in deep-ultraviolet emission from AlGdN thin films pumped by an electron beam

We studied the deep-ultraviolet emission properties of Al0.999Gd0.001N thin films pumped by an electron beam. The Al0.999Gd0.001N thin films were grown on fused silica substrates using an ultra-pure reactive sputtering technique. The intra-orbital electron transition of the Gd3+ ions in Al0.999Gd0.001N showed an extremely narrow luminescence line at 318 nm. We fabricated field-emission devices using an Al0.999Gd0.001N phosphor thin film and analyzed the dependence of the device characteristics on the injected current and acceleration voltage. The maximum output power was 1.0 mW/cm2. The excitation cross section was of the order of 10-13 cm2 and was found to depend on the acceleration voltage. These results indicate that injected high-energy electrons multiply excite Gd3+ ion.