THE INFLUENCE OF SE COEVAPORATION ON THE ELECTROLUMINESCENT PROPERTIES OF SRSCE THIN-FILMS

Ce-doped SrS is a most promising blue-green phosphor for AC thin film electroluminescence. Since evaporated thin SrS films are strongly sulphur-deficient, S co-evaporation is usually performed. As an alternative to this rather contaminating procedure, Se has been added during deposition. This results in the formation of a solid solution SrS1-xSex and in a drastic increase of brightness, with limited vacuum system contamination. When no co-evaporation is performed, the emission spectrum reveals a previously unresolved red peak. Upon the addition of Se, this emission band is largely suppressed. Time resolved spectral measurements permit to indicate the possible mechanisms for the red feature.