Study of Charge Transfer at the Interface of SnO₂ Ultra-fine Particle Film/Gas

SnO₂ film have been deposited on silicon by PECVD （plasma enhance chemical vapor deposition） There are more chemical adsorbed oxygen ions on the surface of SnO₂ film. Detection of SnO₂ thin film resistance to all kinds of gas has been shown that is sensitive only to alcohol. IR and sensitivity of alcohol （CH₃OH, CH₃CH₂OH, CH₃CH₂CH₂OH, HOCH₂CH₂OH）have been taken. Model of alcohol oxidation at SnO₂ surface is obtained. O₂, O₂^2- and O^- at SnO₂ surface are active centers and medium of the charge transfer. O₂^- mainly captures proton from alcohol when O₂^- intethcts with alcohol. O^- mathly contacts and reacts with H on β-C （reverse side of α-COH at same level） Lastly adsorption complex have been spitted to formyloxy. The model have explained character of sensitivity and is theoretical basis of gas sensor designation.