Dual-Gate Field-Effect Transistor Ultrahighly Sensitive Hydrogen Sensors Enabled by an Ultrahigh Inherent Gain

Gas sensors based on a field-effect transistor (FET) have shown great promise owing to the high sensitivity, flexible design, easy fabrication, and compatibility to integrated circuits. However, the advantages of this FET gas sensor have not been fully utilized. In the present work, semiconducting carbon nanotube dual-gate (DG) FET sensors are designed to detect hydrogen with a high sensitivity (∼80 mV/ppm) by introducing an inherent amplification mechanism. Taking advantage of the high gate capacitance ratio between the top and bottom gates in the DG-FET structure, the sensing signal from the top gate can be further amplified with the assistance of the bottom gate through a bridge circuit design, achieving a maximum gain of up to 16.8 dB. The gain is adjustable from 14 to 16.8 dB, enabling an adaptive measurement range. This work provides a universal design to achieve a high inherent gain and then a high sensing performance in practice for low-dimensional semiconductor-based FET sensors.