Field emission dependence on the tilted angle of palladium nanogaps for surface conduction electron-emitter displays

The emission efficiency of novel surface conduction electron-emitters corresponding to tilted angles (θ) of a nanogap-typed driving cathode is optimised. Among the parameters of the emitter profile, the apex angle is the most significant because the smaller angles induce a higher electric field. The higher electric field then attracts more particles into vacuum and then increases the emission current. However, the structure of the driving cathode limits the electron trajectory while the angle decreases, and it reflects that the portion of collected current by the anode decreases and results in a drop in emission efficiency. The electric field with larger tilted angles will be weakened, but most of the emitted electrons could be collected by the anode, which increases emission efficiency. This shows there is highest emission efficiency (about 37) under an optimum angle (θ) of 60° owing to a trade-off between emission efficiency and emitter apex.