▎ 摘　　要

Tin Oxides and tin compound (SnOx-S-n) films with various thicknesses were thermally evaporated onto the chemical vapor deposition (CVD) grown graphene and their sensitivity to the formaldehyde (HCHO) was investigated. It was found that the graphene substrate did not show any chemical inertness for the thermally evaporated SnOx-S-n films, which could be easily grown on the bare graphene films without any functionalization. The Sn was only partially oxidized, and the specific structure of Sn core and SnOx (including SnO2 and SnO) outer shell as well as the mixture of the SnOx and Sn nanoparticles was proposed, in which SnOx atted as highly sensitive reaction centers while the Metallic Sn in association with high conductive graphene substrates formed electron transporting networks: Abnormal p-type response of the SnOx-S-n/ graphene sensors upon the exposure to reducing HCHO was observed probably due to the generation of holes from the reactions of oxygen vacancies and oxygen. The SnOx-S-n/ graphene sensors sensitivity showed strong dependence on the compound films surface morphology, which was closely related to the films thickness and thermal evaporation rate. With the optimal thickness of 1 nm and thermal evaporation rate of 0.1 angstrom/s, SnOx-Sn/graphene sensors response of 24% upon the exposure to 10 ppm of HCHO and the low detection limit of 200 ppb could be obtained The mechanism responsible for such Sensitivity performance was discussed.