Ultrasensitive and selective detection of ammonia gas at room temperature of La-doped ZnO thin films

Ammonia detection is crucial for various applications such as environmental monitoring, industrial processes, and healthcare. Here, we explore the potential of La-doped ZnO thin films as a cost-effective, efficient, and environmentally friendly RT-NH₃ sensor prepared by spray pyrolysis method. Pure and La-doped ZnO films were highly sensitive and selective to ammonia gas as compared to other gases. The 3% La-doped ZnO films were most sensitive to ammonia gas with a relatively high response of about 74.28%, with very fast response time and recovery time of 17 s and 30 s, respectively, at room temperature. The response of 3% La-doped ZnO thin films was about three times greater than that of the pure ZnO films when evaluated under the same conditions. Moreover, the selectivity, sensitivity, reproducibility and long-term stability were also examined. The 3% La-doped ZnO films show a gas-sensing response at a lower concentration of 0.5 ppm of ammonia.