To enhance field emission properties, magnesium oxide (MgO) thin films were coated on the top of aluminum-doped zinc oxide (ZnO:Al) whiskers. The crystalline form of MgO was used as a representative material showing a high secondary-electron-emission An electron emission experiment was performed for 1000h using an emitter consisting of the aggregated MgO/ZnO:Al whiskers. Scanning electron microscopy was conducted to compare the emission site images obtained before and after 1000 h operation. Furthermore, in this paper, Fowler-Nordheim plots are presented to explain the changing phenomenon of the field enhancement factor and the effective work function of the emission site before and after operation. Finally, a model of the electron emission of a MgO/ZnO:Al whisker-type field emitter is proposed.
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