STRUCTURAL CHARACTERIZATION OF LUMINESCENT CA0.95CD0.05S

Cadmium-doped calcium sulphide has great potential as a broadband ligh t source in both powder and thin film electroluminescent devices. We n ow report the first structural investigation of polycrystalline cadmiu m-doped calcium sulphide using a combination of transmission electron microscopy (TEM) with microanalysis, and X-ray diffraction. We show th at the crystals formed by direct reaction of CaS and CdS under excess su Iph ur do not yield an even distribution of cadmium. We also show t hat the crystals are heavily dislocated with defect structures typical of rock-salt structures. We show that TEM can be successfully applied to the study of these moisture-sensitive materials without the format ion of a artefacts and that TEM should be a valuable tool for studying their thin film structures.