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

• Published in: Sensors and actuators. A. Physical. Vol. 362; p. 114665
• Main Authors: Sneha, C., Baiju, Vijayan K., Varghese, Soney
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2023
• Subjects: Hydrogen gas sensor; Sb doping; SnO2 Mesoporous nanostructures; SnO2 Mesoporous nanostructures; Sb doping; Hydrogen gas sensor
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2023.114665

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. [Display omitted] •ATO thin film has been produced using RF sputtering with varying doping concentrations and deposition temperatures.•Low concentration H2 gas with 0.1 ppm level detection was carried out by using MOS-based thin films (ATO thin films).•5 wt.% ATO films at 300 ℃ show the highest surface area and carrier concentration, driving for high gas sensitivity.•Developed ATO film is showing better repeatability and long-term stability.