Formation of ZnGa₂O₄ films by multilayer deposition and subsequent thermal annealing

The Ga₂O₃/ZnO multilayer films are deposited on quartz substrates by magnetron sputtering, the thickness values of Ga₂O₃ layers are in a range of 19 nm-2.5 nm and the thickness of ZnO layer is a constant of 1 nm. Formation of spinel ZnGa₂O₄ film is achieved via the annealing of the Ga₂O₃/ZnO multilayer film. The influences of original Ga₂O₃ sublayer thickness on the optical and structural properties of Ga₂O₃/ZnO multilayer films and annealed films are studied. With the decrease of the thickness of Ga₂O₃ sublayer, the optical band-gap of Ga₂O₃/ZnO multilayer film decreases, the intensity of UV emission diminishes and the intensity of violet emission increases. The annealed film displays the enlarged optical band gap and the quenched violet emission. UV fluorescence bands are observed from Ga₂O₃ and ZnGa₂O₄.