Fabrication of ZnO Thin Film Sensor using Sputtering for Low-level NO2 detection

The accurate detection and monitoring of gas levels in real-world environmental conditions remain a significant challenge. Gas sensing technologies are essential for detecting hazardous analytes such as NO₂, SO₂, CO, NH₃ and H₂S. Among these, detecting NO2 at significant levels continues to pose a challenge. In this context, the present study investigates sputtering-based ZnO thin film gas sensors for the real-time detection of NO2. The fabricated films were characterized to assess their structural, morphological, functional group, optical, and gas sensing properties using techniques such as XRD, FE-SEM, FTIR, PL and the Keithley 2450 Source Meter, respectively. The sensing analysis demonstrated the excellent performance of the fabricated film for NO₂ detection, with an optimum operating temperature of 200°C, achieving a 52% response at a concentration of 200 parts per million (ppm), along with a sensing response time of 44 seconds and a recovery time of 530 seconds. Furthermore, the sensor exhibited a detection limit as low as 43 ppb. The findings of this research underscore the significant potential of sputtered ZnO thin films as reliable and versatile candidates for advanced gas sensing technologies, paving the way for further innovations in environmental monitoring and safety applications.