Combinatorial deposition of EL phosphor thin films by r.f. magnetron sputtering using a subdivided powder target

A new technique incorporating combinatorial deposition by r.f. magnetron sputtering was used to develop new Eu-activated multicomponent oxynitride thin-film phosphors for electroluminescence. By sputtering with a powder target that is subdivided into two parts, phosphor thin films with a chemical composition that varied across the substrate surface could be successfully prepared. Thin-film electroluminescent (TFEL) devices were fabricated incorporating various Eu-activated phosphor host materials such as multicomponent oxynitrides: GaN, AlN or Si3N4 combined with Ga2O3, CaO or ZnO. In ((AlN)1−X–(CaO)X):Eu thin films, for example, the chemical composition (CaO content (X)) could be optimized to obtain higher electroluminescent and photoluminescent emission intensities by using only one deposition with the new technique. As a result, a luminance of 170 cd/m2 for red emission was obtained in an ((AlN)0.1–(CaO)0.9):Eu TFEL device driven at 1 kHz. High luminances were also obtained in red-emitting-TFEL devices using either a ((GaN)0.9–(Ga2O3)0.1):Eu or a ((GaN)0.8–(ZnO)0.2):Eu thin film prepared with an optimized composition.