Development of Columnar Tin-Doped Gallium Oxide Films Using an RF/DC Cosputtering Technique of Dual-Procedure for Hydrogen Sulfide Sensing Applications

This research presents the development of a Sn-doped gallium oxide (Sn-d-GO) thin-film-based MEMS gas sensor with enhanced sensitivity, stability, and selectivity. By employing radio frequency (RF)/direct current (DC) co-sputtering and MEMS fabrication, high-quality Sn-d-GO films were achieved, offering precise stoichiometry and scalability. Key process optimizations, including dual-procedure deposition and annealing at 197.2 °C, resulted in significant impedance reduction and improved sensor stability. The sensor demonstrated a 39.5% response to 1 ppm H2S and reliably detected concentrations as low as 62.5 ppb, with response and recovery times of 12.1 and 32.2 seconds, respectively. Selectivity tests confirmed superior H2S detection over CH4, SO2, NH3, and CO, with minimal effect from humidity or ambient temperature variations. Analytical techniques, such as SEM, TEM, and XPS, validated the structural and compositional integrity of the Sn-d-GO films. These results highlight the sensor's potential for practical gas sensing applications, offering robust performance and scalability for advanced environmental monitoring.