Surround Gate Nanoscale Air-Channel Transistors via Ion Implantation Process for Amplification Applications

Nanoscale air-channel transistors (NACTs) are promising candidates for high-frequency, high-speed, and radiation-resistant applications. However, in existing three-terminal NACTs, the gate primarily controls the electric field near the source and within the air channel. This limitation hinders the achievement of saturation characteristics of the devices that restrict their applicability in amplifiers. It is also challenging for small gate voltages to effectively regulate output current. Additionally, the gate captures electrons emitted from the source, leading to significant gate leakage current issues. This paper introduces a novel surround gate NACT, employing IC-compatible fabrication techniques. The source is realized by N-type doping on a P-type silicon substrate using ion implantation process. This approach allows for effective control of electron concentration with small gate voltages, significantly altering both the emission electron number and the output current. The saturation output characteristics of the proposed NACTs are demonstrated experimentally, with the gate leakage current effectively reduced to the pA level. Additionally, an amplification circuit with a gain of 6.96 dB at 1 kHz and a cutoff frequency of 8.6 kHz is achieved. Our results provide a feasible method for the challenges of poor gate control capability and high gate leakage current of NACTs, demonstrating their significant potential in high-frequency amplification applications.