High Sensitivity of Porous Cu-Doped SnO 2 Thin Films to Methanol

Abstract

Porous Cu-doped SnO 2 thin films were synthesized by the sol-gel dip-coating method for enhanc-ing methanol sensing performance. The effect of Cu doping concentration on the SnO 2 sensibility was investigated. XRD data confirm that the fabricated SnO 2 films are polycrystalline with tetra-gonal rutile crystal structure. AFM and SEM micrographs confirmed the roughness and the poros-ity of SnO 2 surface, respectively. UV-Vis spectrum shows that SnO 2 thin films exhibit high trans-mittance in the visible region ∼95%. The band gap (3.80 -3.92 eV) and the optical thickness (893 -131 nm) of prepared films were calculated from transmittance data. The sensing results demon-strate that SnO 2 films have a high sensitivity and a fast response to methanol. In particular, 3% Cu-SnO 2 films have a higher sensitivity (98%), faster response (10 −2 s) and shorter recovery time (18 s) than other films.