Impact of O2/Ar gas ratio on the DC reactive magnetron sputtered NiO thin films for ultrafast detection with high sensitivity and selectivity towards H2S gas

H2S is one of the most hazardous gases, causing several serious health consequences. In the present work, room temperature DC reactive magnetron sputtered NiO thin films were prepared on alumina substrate to detect H2S gas. The O-2/Ar gas ratio (10 % and 20 %) influenced the presence of defects (Ni3+/Ni2+) as investigated by XPS studies, and had a substantial impact on the H2S gas sensing performance. The NiO thin film deposited at 20 % O-2/Ar ratio exhibited highly improved sensing compared to the film deposited at 10 % O-2/Ar ratio. The highest SR similar to 14.8 at 350 degrees C with an ultrafast response time (35s)/recovery time (14s) was achieved for the NiO thin film prepared at 20 % O-2/Ar ratio towards 100 ppm H2S gas. An excellent SR similar to 5.8 was obtained at a relatively low T-op of 175 degrees C. Further, the high sensitivity and selectivity of NiO thin films make them a prospective material for low ppm (similar to 3 ppm) H2S gas detection.

Automated summary

In this study, room temperature reactive magnetron sputtered NiO thin films were prepared to detect H2S gas. The influence of O2/Ar gas ratio on the sensing performance was investigated, and it was found that the NiO film prepared at 20% O2/Ar ratio exhibited highly improved response rate and response time, showing potential for low ppm H2S gas detection.