Theoretical Approaches toward Designing Sensitive Materials for Carbon Nanotube-Based Field-Effect Transistor Gas Sensors

Screening sensitive materials is one of the keys to designing high-performance carbon nanotube-based field-effect transistor gas sensors. Here, we proposed a reliable way (e.g., H2S) to design sensitive materials with high efficiency based on theory and experiment. Our results demonstrated that the interaction between H2S and the sensitive materials must satisfy both energy level and parity match, and the maximum overlap of the orbital wave function. Especially, the gas ΔQ exhibits a strong linear scaling with the metal φ (ΔQ∝φ). Meanwhile, Δφ will result in changes in the threshold voltage of the sensor (ΔVth∝Δφ) in experiments, which would lead to different response intensities. Therefore, the greater the ΔQ, the more changes in the threshold voltage, and corresponding higher response intensity. Expectedly, our experimental results show that the response intensity at equivalent concentrations is in high agreement with the theory (Pt > Pd > Ag), and the limit of H2S detection is low to 20 ppb.