Antimony doped tin oxide MOS sensors for hydrogen detection at low concentrations

In this study, Antimony (Sb) doped tin oxide (SnO2) thin films (ATO) were synthesized using the RF (radio frequency) sputtering technique with varying antimony concentrations (0, 3, 5, 7 wt%) and substrate temperatures of room temperature, 150 ℃, and 300 ℃. It was discovered that these thin films were tetragonal crystal structures with good crystallinity and grew preferentially along the (101) planes at the substrate temperature of 300 ℃. It was found that the 5 wt% doped film prepared at 300 ℃ substrate temperature exhibited superior gas-sensing properties under all tested conditions, and the 7 wt% doped sample showed properties that deviated from the trend observed up to 5 wt%. It was observed that the morphology of the film has a spongy spherical granular structure with a mesoporous surface. The presence of Sn, Sb5+/Sb3+, and oxygen was confirmed by XPS spectra analysis in the thin films. The n-type electrical conductivity was attained by combining an oxygen vacancy and antimony ions in the tin oxide lattice interstitial. Consequently, the inclusion of antimony increased conductivity up to 5 wt% was noticed. Doping makes remarkable changes in surface roughness (14–163.48 nm), which is attributed to the surface wettability. The film turns nearly hydrophilic when the doping concentration increases (59°). According to studies into a potential gas-sensing mechanism, the addition of Sb dopants, mesoporous structures, and high specific surface area was thought to be the reason for the improved gas-sensing response. Without a doubt, the current work may offer the best method to enhance H2 gas response in particularly environmentally sensitive applications.