Reducing the gate current in vacuum channel field-emission transistors using a finger gate

A nanofinger gate vacuum field-emission transistor with a vertical channel (FGVFET) is proposed herein. The reduction of the gate leakage current is investigated to obtain an optimum structure. The proposed three-terminal metal–insulator–metal device with a 43-nm vertical vacuum channel is capable of operating in air ambient and provides a high anode drive current (101 µA), while both the gate and anode voltages are small at about 5 V. Meanwhile, the gate leakage current of the FGVFET is reduced by about sevenfold compared with conventional structures. Also, this vacuum transistor exhibits a low threshold voltage (0.55 V) that is comparable to modern solid-state devices. As a result, a significant cutoff frequency (f_T) of 1.13 THz is obtained. Other electrical characteristics of the FGVFET, such as the on–off current ratio and transconductance, are also calculated. The introduced modification could be applied to other vacuum vertical-channel transistors to provide a new class of high-speed low-power transistors for digital applications.