Electronic And Optical Properties Of Graphene Modified By Metal Chlorides

Graphene is a new type of carbon nanomaterial, which has outstanding properties,especially its optical and electronic properties, e.g, ultra-high conductivity, high opticaltransmittance. Single layer graphene exhibits a linear band dispersion near the Diracpoint, and this linear band extends to UV range (300nm). Absorption of graphene isconstant from far-infrared to ultraviolet due to this linear band. These unique optical andelectrical properties make graphene possess a wide range of applications in photonicsdevices. Graphene can be used for fabrication of transparent electrode, photovoltaicdevices, electroluminescent devices, optoelectronic devices and touch screens. However,pristine graphene has relative high sheet resistance. In order to reduce the sheetresistance, increaing of carriers in graphene is needed. This thesis discusses the way ofreducing sheet resistance in graphene effectively, and at the same time make sure thetransmittance of graphene is more than90%in the visible light range.The first part of this thesis introduces physical and chemical properties of grapheneas well as its future applications. The second part introduces the normal fabricationmethod of graphene, which focuses on the two frequently-used methods in thelaboratory, mechanical exfoliation method and chemical vapour deposition method,advantages and disadvantages of those two methods are compared. The third partintroduces the characterization techniques of graphene, which focuses on the opticalmicroscopy and Raman spectroscopy. The Raman features of grpahene are introducedwhich will provide guidance for future study.The fourth part of this thesis is the most important part. Metal chlorides are used tochemically doping graphene and layer-by-layer doping graphene method to modify theoptical properties of graphene. It is found that after transferring three layers dopedgraphene, the sheet resistance of graphene layers is lower than300/sqand thetransmittance in the visible range is still more than90%. In addition, graphenedecorated with metal nano particles are fabricated, the surface plasmon resonanceabsorption from nanoparticle in the visible light range is observed. The Ramanenhancements of graphene and rhodamineB（RhB）molecules are obserbed. Usinggraphene decorated with metal nano particles as a substrate for detecting targetmolecule, the flate surface of graphene is easily for molecules to adsorbed on, and theuniformly dispersed nanoparticles can be used to enhance the local field, therebyenhancing molecule Raman signal.