Selective Room-Temperature Ultrasensitive Detection of H₂S Using Au/Pd Functionalization in Si-Field-Effect Transistors

It is becoming increasingly crucial to accurately detect and quantify toxic gases for safety in manufacturing, mining, agriculture and automobile industries. Current technologies impose a challenge of high-power consumption due to assisted recovery, cross-sensitivity, temperature/ humidity dependence, and aging of resistive sensors, which result in poor reproducibility. We present chemical-sensitive field effect-transistors (CS-FETs) fabricated on bulk silicon with Au-Pd alloy surface-functionalization, operating at room temperature with low power consumption. The thin sensing layer on the silicon channel can be modulated to switch the gate in the presence of 50 ppm H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>S gas with changes in drain current response of >200% within 120 s, followed by unassisted recovery at room temperature and with a power consumption < 20 μW. The multi-gas detection capabilities, for NH3 and NO2 were also studied and exhibited current responses of -21.9 to 11.5%, and -24.2 to 13.8%, respectively, in contrast to the highest sensitivity to H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>S of ‒52.6 to 28.8%. This low-power and highly sensitive H<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>S sensor offers an advantage over existing bulk resistive sensors and will support the future development of single-chip, low-power, multi-gas electronic nose devices that can be mounted wirelessly for remote applications.