Spindt-type field emitters have a relatively wide emission angle of about 30 degree. To realize an ultra-fine field emission display (FED), focusing electron beam is necessary for avoiding crosstalk. Double-gated field emitters with a focus gate electrode are a promising emitter, because electron beam can be relatively easily focused in symmetric shape. However, the emission current is drastically reduced due to the influence of the lower potential of the focus gate electrode than that of the extraction gate electrode [1]. Figure 1 shows the simulation result of the dependence of the electric field at the top of the emitter tip on the thickness of the extraction gate electrode. In the simulation, the bias voltages of the focus electrode and gate electrode were 57 and 70V, respectively. Both apertures of the focus and gate electrodes were 1μm. As shown in Fig.2, the electric field at the tip decreases when the lower potential than that of the gate electrode is applied to the focus electrode. However, the electric field increases with increase of the gate thickness, due to the shielding effect of the thick gate electrode. At the gate thickness of 1μm, the electric field recovers the initial field strength without operation of the focus electrode.
展开▼
