SIMULATION OF THE ELECTRICAL CHARACTERISTICS OF FIELD-EMISSION TRIODES WITH VARIOUS GATE STRUCTURES

A new two-dimensional numerical simulation which can accurately reprod uce the empirical electrical characteristics of vertical field-emissio n triodes (FET's) with various gate geometries has been developed. The electrical characteristics of volcano-shaped-gate FET's were simulate d for the first time and compared with those of planar-gate ones. Volc ano-shaped-gate FET's exhibit significant advantages over planar-gate ones due to their superior current-voltage (I-V) properties and larger tolerance of fabrication error. A reasonable definition of emission a rea was obtained by applying the non-uniform current density model. Fo r sub-micron gate aperture, the gate current is obvious only if the de vice structure is deeply tip-recessed. On the basis of the evaluation of the device structures including the tip cone angle, the related tip -to-gate height, the emitter shape, and the shrinkage of gate aperture , a high-aspect-ratio conical emitter with a small tip radius will be the optimum structure of FET's for low-voltage operation.