Room-temperature high-sensitivity hydrogen sensing using Pd/Al2O3/IGZO TFT with ultrathin ALD Al2O3 passivation-transport layer

ABSTRACT The development of room-temperature hydrogen microsensors still faces technical challenges. In this work, we report a Pd/Al 2 O 3 /IGZO thin film transistor (TFT) hydrogen sensor chip, which exhibits excellent hydrogen detection performance at room temperature. The sensor achieves a relative response of 100.2 to 1000 ppm hydrogen, a detection limit lower than 20 ppm, and a device area of 0.75 mm 2 . By inserting an ultrathin Al 2 O 3 passivation-transport layer between the IGZO channel and Pd gas-sensing layer using atomic layer deposition technology, and precisely tuning its thickness to the sub-nanometer scale, the Pd/IGZO interface defects are effectively suppressed while permitting efficient coupling between the gas-sensing signal and the channel current. This prevents the injected carriers from being trapped at interface states, significantly improving the sensitivity of hydrogen detection. Biasing the TFT in the subthreshold region further amplifies the sensing signal through gate-controlled carrier modulation. Moreover, the entire preparation process of the sensor chip is compatible with the complementary metal-oxide-semiconductor manufacturing process, which provides feasibility for the mass production of micro gas sensors. The technical solution proposed in this work not only provides a manufacturing approach for room-temperature H 2 sensors compatible with micro processing technology but also promotes the application of TFT in the field of gas sensing.