Effects of Substrate Temperature during Phosphor Layer Deposition on Luminance of SrS:Ce Blue-Green-Emitting Thin-Film Electroluminescent Devices

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Abstract
In order to improve the luminance of blue-green-emitting SrS:Ce thin-film electroluminescent devices, the effects of substrate temperature (350-550°C) during phosphor layer deposition were studied. Two deposition procedures were used: sulfur coevaporation and sulfurization of evaporation sources. The luminance increased with increasing substrate temperature in both cases. As the substrate temperature increased, oxygen content decreased and sulfur content remained almost constant for coevaporation; however, sulfur content increased while oxygen content remained low when the sulfurization technique was used. These changes led to improvement in the crystallinity of the phosphor layers. Also, sulfur and oxygen contents in phosphor layers deposited at 550°C by both procedures were almost the same, and as a result, the luminance levels were almost the same.