Preparation And Contact Properties Of FTO/Graphene-based Materials Heterostructure Composite Film

In this paper,the fluorine doped tin dioxide?FTO?film and reduced graphene oxide?rGO?heterostructure composite film?FTO/rGO/FTO?was prepared by the method of aerosol-assisted chemical vapor deposition?AACVD?and spin-coating.The FTO film and graphene?G?composite film?G/FTO?was fabricated by the physical transfer method.The structure,morphology,optical and electrical properties of FTO/rGO/FTO composite films were studied by X-ray diffraction?XRD?,transmission electron microscope?TEM?,field emission scanning electron microscope?SEM?,ultraviolet-visible spectrophotometer,four-probe square resistance test and Hall effect measurement system.The structure,surface morphology and distribution of element in the G/FTO composite film were studied by Raman spectrometer,SEM and TEM.The kelvin probe force microscope?KPFM?and the conductive atomic force microscope?C-AFM?are based on the atomic force microscope?AFM?,which can obtain the surface topography,the CPD and I-V curves,etc.The main results are as follows:The optical and electrical properties of FTO/rGO/FTO composite film are connected with the concentrations of reduced graphene oxide.When the concentration of reduced graphene oxide is 0.2 mg/m L,the minimum sheet resistance,resistivity,average transmittance,thickness and the carrier concentration are about 6.4?/?,3.90×10^-4?cm,73.1%,608.6 nm and?10²⁰ cm^-3,respectively.With the increase of the concentration of rGO,the average transmittance of the composite film decreases gradually.The optical and electrical properties of FTO film could not be enhanced by the appropriate concentration of rGO.Fluorine was uniformly doped into the lattice of tin dioxide?SnO₂?.The FTO film and rGO contact closely and form a good contact interface.Besides,compared with the compressed air,FTO film has better optical and electrical properties when the compressed nitrogen is used as carrier gas.The electrical properties of G/FTO composite film are better than FTO film,which the resistivity of them are 3.55×10^-4?cm and 3.78×10^-4?cm,respectively.When graphene is contact with the FTO film,the charge transport from FTO film into graphene,which makes the carrier concentration and mobility are increased and barrier height is decreased.When contacting with FTO film,graphene is not affected by the fluctuation of pyramidal particles and evenly distributed on the surface of the FTO film.Finally,it will form a good close contact.The contact potential differences are-0.474 V and-0.441 V,which the calculated work function are 5.329 eV and 5.296 eV for FTO film and G/FTO composite film,respectively.By studying the Hall effect of two samples and comparing with each other,the mobility were raised from 21.26 cm² V^-1 s^-1 to 23.82 cm² V^-1 s^-1 for FTO film and G/FTO composite film,respectively.The I-V curves have a significant difference between FTO film and G/FTO composite film.If the FTO film and the G/FTO composite film are regarded as two independent systems,the calculated barrier heights are 0.39±0.06 V and 0.33±0.05 V.The barrier heights of the G/FTO composite film is smaller than the FTO film.The electric charge transport from FTO film into graphene,which increasing the mobility and reducing the contact barrier.