Effects of Oxygen in CaS:Eu Active Layers on Emission Properties of Thin Film Electroluminescent Cells
- 1 August 1990
- journal article
- Published by IOP Publishing in Japanese Journal of Applied Physics
- Vol. 29 (8R) , 1495-1498
- https://doi.org/10.1143/jjap.29.1495
Abstract
CaS:Eu active layers for thin film electroluminescent (TFEL) cells were deposited by the electron beam evaporation method under several partial pressures of oxygen, and the effects of oxygen in CaS:Eu active layers on EL characteristics were studied. With increased deposition pressure, the amount of oxygen in the CaS:Eu thin films increased. The EL efficiency and PL intensity due to Eu2+ ions decreased, and absorption intensity due to Eu2+ ions decreased. In addition, Eu3+ emission peaks were observed in the EL spectrum of the cell prepared at a higher deposition pressure (3×10-2 Pa). From these results, it was concluded that oxidation of Eu ions (Eu2+→Eu3+) occurred and the concentration of Eu2+ ions decreased by adding oxygen during active layer deposition.Keywords
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