Nickel-sensitized Sb: SnO2 thin films for enhanced room temperature hydrogen gas sensing

Abstract

This study presents the development of hydrogen gas sensors operating at room temperature, utilizing DC-sputtered nickel (Ni) catalysts patterned in an island-like morphology on RF-sputtered antimony-doped tin oxide (Sb: SnO₂) thin films. The Ni deposition was systematically varied by adjusting deposition times from 0 to 20 min in 5-minute increments, with characterization via SEM-EDS confirming the Presence of Ni and other deposited elements. XRD analysis showed a progressive enhancement in the Ni peak intensity at 2θ = 44.83° as deposition time increased. The patterned Ni significantly altered the surface roughness of the Sb: SnO₂ films, leading to notable changes in wettability, including increased hydrophobicity at 15 min of deposition. However, at 20 min, excessive Ni coverage hindered gas adsorption, reducing sensor performance. The activation energy for hydrogen detection decreased significantly, from 3.12 eV for Sb: SnO₂ films to 1.19 eV with Sb: SnO₂-Ni (15 min), as determined using the Arrhenius equation. Sensors with 15 min of Ni deposition demonstrated optimal performance, detecting 0.5 ppm hydrogen at 25 °C, with a response of 3.36 % and rapid response/recovery times of 6/9 s. These enhancements are attributed to Fermi energy alignment and the spillover mechanism. The Sb: SnO₂-Ni (15 min) sensor exhibited excellent stability over 42 days, good repeatability, and linearity. Humidity tests showed the response decreased from 40 % to 8 % for 10 ppm hydrogen as relative humidity increased from 35 % to 85 %. This study highlights a novel Ni patterning on the Sb: SnO₂ film approach for enhanced hydrogen sensing performance at room temperature.