Effect of nanoscaled SnO2 coating on ZnS:Mn phosphors under electron irradiation

The luminescence properties of SnO2-coated ZnS:Mn phosphors are investigated. In the case of photoluminescence, emission intensities show little change when SnO2 is coated on the surface of ZnS:Mn, while in the case of cathodoluminescence (CL), emission intensities vary depending on excitation energies. In order to determine the luminescence behaviors, surface analyses of the phosphors were performed. Auger electron spectroscopy showed that the width of the SnO2 layer on the ZnS:Mn phosphor was saturated at approximately 120 nm. Also, X-ray photoelectron spectroscopy indicated that the SnO2 layers are well formed and saturated when the molar ratios of Sn/Zn are larger than 0.005. These results suggest that the changes in the CL emissions can be attributed to a lowering of the junction barrier.