Fabrication of metal field emitter arrays on polycrystalline silicon

Cone-shaped metal field emitter arrays were fabricated on a single heavily doped polysilicon layer. From the observation of the metal field emitter fabricated on the single-polysilicon layer, it was noticed that the irregular shape of the gate aperture was caused by the large grain size of heavily doped polysilicon after oxidation. Therefore, in order to obtain a good shape, the double layers of polysilicon where one was heavily doped and the other was not doped were used. The undoped polysilicon layer was consumed for the gate oxide layer and the doped polysilicon layer was used to serve as a conducting cathode layer. The small grain size of the undoped polysilicon after oxidation led to an improved shape of the gate aperture which rendered a stable emission characteristic.