Investigation On Fabrication And Properties Of Graphene And C/Ti Laminated Films

Graphene owns a series of excellent properties. It receiveed a lot of focus since it was discovered.Recently, chemical vapor deposition has become the research focus of graphene material preparationas the most common method to grow graphene with large scale and high quality. The carbon/titaniummultilayers has some unique electrical and optical properties. It also has important research value.In this thesis, graphene was deposited on copper foil using polystyrene as a solid carbon sourceby low pressure chemical vapor deposition with two heat zones. The effects of solid sourcetemperature and substrate temperature were studied. Films deposited under different conditions werecharacterized by Raman spectroscopy, UV/VIS Spectrophotometer and scanning electron microscope.It was found that the solid source temperature influenced the concentration of carbon source directly.The number of layers of graphene could be controlled by changing the solid source temperature.Substrate temperature made a big impact on the catalytic ability of copper substrate. The defects andlayers became less when the substrate temperature rose. The dynamic change of solid sourcetemperature could reduce the nucleation density and break the balance of graphene growth andhydrogen etching, which resulted in a raise of graphene grains’ size and coverage. Eventually, singlelayer graphene with high quality and coverage was deposited at a substrate temperature of1000℃with the dynamic change of solid carbon source temperature.Then, graphene films were grown on copper foil at low temperature by hot-filament chemicalvapor deposition, using acetylene as carbon source. The results indicated that the raise of thetemperature of hot-filament helped graphene grow better since it improved decomposition ofacetylene to carbon active groups which could promote the formation of graphene. The change ofsubstrate temperature from350℃to450℃also improved the crystallization of graphene filmsbecause of the enhancement of copper substrate’s catalysis capability. The layer number of graphenecould be reduced by controlling the percentage of acetylene in the forming gas. Finally, a single layernanocrystalline graphene was obtained at a low substrate temperature (450℃), with2%acetylene anda hot-filament temperature of1800℃.As the third part, magnetron sputtering method was used to grow amorphous-carbon films,titanium films and the amorphous-carbon/titanium multilayers, and to explore the influence of thethickness of titanium layer and air atmosphere annealing on the optical and electrical properties. Theresults showed that during the annealing process, titanium oxidized. With the annealing pressure increase, the transmittance of titanium films raised and its electrical conductivity decreased. Thetransmittance of amorphous-carbon also increased as the annealing pressure increased.Amorphous-carbon was contracted during the annealing in air, forming some strip structures with atransmittance of98.6%. The multilayers were affected by the changes of titanium andamorphous-carbon during the annealing process. Its transmittance raised but its electrical conductivitydecreased as the annealing pressure increased. The increase of titanium layer thickness could improvethe electrical conductivity of the multilayers, but would reduce film’s transmittance. With the increaseof annealing temperature, film’s transmittance was promoted, but electrical conductivity decreased.