Improvement of Luminescent Properties of Phosphor Powders Coated with Nanoscaled SiO₂ by Atomic Layer Deposition

An investigation is reported by coating BaMgAl10O17:Eu2+ phosphor by silicon oxide using catalyzed atomic layer deposition. Nanoscaled SiO2 films were prepared at room temperature using tetraethoxysilane (TEOS), H2O and NH3 as precursors, reactant gas and catalyst, respectively. AES analysis showed the surface composition of coated phosphor was silicon oxide. In TEM and FE-SEM analysis, the growth rate was about 0.7 Å/cycle and the surface morphology became smoother and clearer than that of uncoated phosphor. The photoluminescence intensity (PL) increased up to 11.04% as ALD cycle increased up to 200 ALD cycle. This means that the reactive surface of uncoated phosphors is uniformly grown with stable silicon oxide to reduce the dead surface layer without change of bulk properties. Moreover, it is found that nanoscaled SiO2 films are quite effective for the improvement of the aging characteristics of photoluminescence.