Uniform Current Supply in Gated P-Type Si-Tips for Achieving High-Performance Field Electron Emitter Array

The field electron emission current from the gated p-type Si-tips is supplied from the generation current in the substrate depletion. Herein, an inversion electron diffusion model coupled with generation electron injection was established to describe the current supplied for p-type Si-tip array, which is further calculated using finite element simulation. It was found that the inequivalence of geometric position of the tips in the gate pad induces nonuniform current supply. Typically, in a square array, the current supplied for the tips at the out-edge and especially the corner of the array is much higher than that of the tips inside. A narrower tip-to-tip separation results in a poorer current supply uniformity. A ring array, in which the tips are in equivalent position that with uniform current supply, was proposed. Gated p-type Si-tip array in square (20 $\times$ 20) and ring (400 tips) arrangement was fabricated and characterized, respectively. The ring array achieves a high emission current (389 $\mu $ A at 182.6 V and $\sim$ 1 $\mu $ A/tip in average) and uniform ring-shape emission sites. However, the square array showed a lower emission current (64 $\mu $ A at 180 V) and nonuniform emission, which is well consistent to the simulation results. The uniform electron supply in the ring array ensures the tips to uniformly contribute for a high-current emission.