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

Abstract

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 Si 3N 4 combined with Ga 2O 3, 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/m 2 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–(Ga 2O 3) 0.1):Eu or a ((GaN) 0.8–(ZnO) 0.2):Eu thin film prepared with an optimized composition.