CVD Graphene Storage And Natural Doping And Residual Strain

Nanomaterials are an important research field at the national strategic frontier,and graphene,as the most representative material in the family of two-dimensional materials,has excellent electrical,mechanical,optical and magnetic properties,and its application prospects in electronics,energy,catalysis and photoelectric detection are great.With the extensive attention and large investment from the state and society in the field of graphene,the industrialization of graphene has developed rapidly;meanwhile,with the gradual clarification of the division of labor in the graphene industry chain,the storage of graphene materials has become more and more important in the structure of the graphene industry system.Currently,chemical vapor deposition(CVD)based on copper substrate has become the mainstream method to prepare large-area,high-quality monolayer graphene films with its excellent quality,but there are still defects,grain boundaries,and folds in the graphene films prepared by this method,and these structurally imperfect regions provide an entry point for the oxidation of the copper substrate under the film cover after the film preparation is completed.Based on this,this thesis investigates the effect of humidity in the storage environment on the storage of "graphene/copper" and the effect of copper surface in "graphene/copper" on the graphene films before and after transfer,including:The effect of ambient humidity on the oxidation of copper foil covered by graphene films.Continuous monolayer graphene films based on polycrystalline copper substrates prepared under the same conditions were stored in a natural environment with uncontrolled humidity(RH: 50%-80%),in a dry cabinet with low and stable humidity(RH: 30%)and in a humid tank with high and stable humidity(RH: 99%)after 10,20 and30 days,respectively,using optical microscopy(OM),scanning electron microscopy(SEM),atomic force microscopy(AFM),Raman spectroscopy and X-ray photoelectron spectroscopy were used to characterize the graphene films before,during and after transfer to silicon wafers by wet transfer.The results showed that the surface oxidation of copper foil covered by graphene film is difficult to avoid,but low ambient humidity can significantly slow down the surface oxidation rate of copper foil covered by the film.The effects of surface oxidation of copper foil on the continuity of graphene films,doping concentration in the films and strain distribution were investigated.The doping concentration and strain distribution in graphene films obtained by transferring immediately after preparation and after 90 days of storage in a natural environment with unstable humidity were compared with the preparation of discontinuous monolayer graphene crystal domains based on single-crystal copper foils with crystallographic surface indices of(323)and(014),and the doping and strain in the same graphene film region were also tracked during the storage and storage process.The doping and strain in the same graphene film region before and after transfer were compared for 90 days of storage and placement.The results show that although the copper oxide particles formed by the oxidation of copper foil cause p-type doping and change the strain distribution in the graphene films on copper before transfer,this effect is not transferred to the graphene films after transfer.