Focusing Properties of Volcano-Shaped Dual-Gate Field Emitters

Field emitters are used as distributed electron sources in applications such as field emission displays (FEDs) and electron guns. In this study we analyze the deflection and focusing properties of volcano-shaped dual-gate emitters, which has been considered for the first time in this context. The structure considered has a volcano-shaped extracting gate, recessed with respect to the emitter, allowing the focusing gate to be more efficient. The simulation results have been obtained using the Simion 3D 6.0 software package. The analysis refers to the electron beam spot diameter on the anode plane as function of the focusing voltage and the position and size of the focusing gate. An optimal position and size of the focusing gate, which depends only slightly on the focusing voltage, has been shown to exist.