ZnS:TbOF thin films sputter deposited from a single versus separate ZnS and TbOF targets

Thin film ZnS:TbOF electroluminescent (EL) phosphors were radio frequency magnetron sputter deposited from either a single pressed powder ZnS:TbOF (1.5 mole % of Tb) target, or two separate sources consisting of a chemical vapor deposited grown, undoped ZnS target and a TbOF pressed powder target. From two separate ZnS and TbOF targets, the maximum EL brightness at 40 V above the threshold voltage (B40) was 44 cd/m2 with a Tb+3 concentration between 3 and 4 mole %. From a single pressed powder ZnS:TbOF target, the maximum B40 was 89 cd/m2 and the Tb+3 concentration in the film was about 4 mole %. X-ray diffraction and transmission electron microscopy analyses show that films deposited from a single ZnS:TbOF target had a better crystallinity and larger grain size. The lower brightness and poorer crystallinity in the film deposited from two separate ZnS and TbOF targets were attributed to damage from negative ion resputtering