A Carbon-Based FET-Type Sensor With Floating Sensing Gate for ppb-Level Ammonia Detection at Room Temperature

Transition metal dichalcogenides (TMDs) have been widely concerned for the ability to recognize ammonia even operating at room temperature. However, it encounters a bottleneck in the detection of trace ammonia, and the fundamental reason is that the change in the electrical signal of sensing materials caused by trace gas might be too weak to be detected. Herein, a carbon-based field-effect transistor (FET)-type gas sensor is designed by using carbon nanotubes (CNTs) as the channel, yttrium oxide (Y2O3) as the gate dielectric layer, and Au/WS2 as the floating sensing gate. Based on the amplification effect of FET, the as-proposed carbon-based FET gas sensor can achieve the detection of ammonia as low as 100 ppb without additional heating devices and exhibit an excellent selectivity to ammonia over other interfering gases. The excellent gas sensing performance may be mainly attributed to the outstanding amplification effect of carbon-based FET to weak electrical signal and the independent recognition of target gas by the sensing layer separated from the active layer. This work will provide an inspirational train of thoughts for the design of gas sensors in the detection of trace gases at room temperature.