Controlling the structure and composition of SnO₂-based thin film with reactive sputtering to improve the sensitivity of semiconductor CO₂ sensor

The sensitivity of SnO₂ thin film-based CO₂ gas sensors was enhanced by controlling the surface structure employing reactive sputtering during the deposition process to carefully adjust the oxygen partial pressure to modify the surface structure of the SnO₂ films. This process increased the sensitivity, primarily due to larger surface area and improved gas adsorption capabilities. Furthermore, the effect of heterojunctions between p-type SnO and n-type SnO₂ on the sensitivity was investigated using a model diagram. Both theoretical analysis and experimental data consistently demonstrated that the number of heterojunction interfaces contributes significantly to the sensitivity of SnO-SnO₂ heterojunction gas sensors. These findings highlight the effectiveness of controlling the surface structure and composition ratio of thin films through reactive sputtering to enhance sensitivity. This study offers valuable insights for optimizing SnO₂ thin-film-based gas sensors for CO₂ detection.