High-Sensitivity NO2 Gas Sensor Based on Zn-Doped Indium Oxide

This study investigated the crystal structure, surface morphology, and sensing properties of Zn-doped indium zinc oxide (IZO). IZO thin films were deposited onto a four-finger structure using RF sputtering with varying oxygen ratios to enhance sensing performance. SEM analysis revealed a petal-like structure with a preferential growth orientation along the (222) direction. In contrast, X-ray photoelectron spectroscopy (XPS) analysis demonstrated surface OL and OV. In this study, the NO2 detection range was 100–5000 ppb. When exposed to 1000 ppb of NO2, the sensor exhibited a response of 9.39 ( $\Delta {R}$ / ${R} _{\text {air}}$ ) with a response time of 22 s and a recovery time of 23 s. Compared to other gases, including H2S, CO, H2, and NH3, the sensor demonstrated excellent selectivity, which can be attributed to the petal-like structure and the presence of OV and Oads. These characteristics make the sensor highly promising for applications requiring high sensitivity and selectivity in NO2 detection.