Study On Graphene Etching And Modification Based On Ultrafast Laser

Graphene has enormous commercial potential in the application of light-emitting displays,solar cells,and transistors in terms of high light transmittance,high flexibility,high electron mobility and high thennal conductivity.However,the patterning of graphene is difficult,and it is also difficult to prepare a dielectric layer on the surface of it when building a transistor,due to the lack of dangling bonds.In this thesis,our main results are focused on these two issues of graphene as follows:(1)The 532 nm nanosecond laser with different energy densities(26.88 mJ/cm2-81.35 mJ/cm2)was used to etch the graphene to achieve patterning.The experimental results show that the graphene can be completely etched without damaging the substrate under the laser energy density between 41.73mJ/cm2 to 65.43mJ/cm2,however,the actual finished pattern boundaries are not clear.(2)Graphene was prepared by methane pyrolysis on the surface of the copper foil by using chemical vapor deposition(CVD).The graphene was etched by picosecond laser with different energy densities(0.5J/cm2-1.0J/cm2)and scanning speed(100cm/s-300cm/s),and the pattern quality was significantly improved.The pattern boundary of graphene is clear etched by the laser with energy density of 0.8 J/cm2,and the scan speed of 100 cm/s.(3)The quality of the alumina layer grown on the surface of graphene was significantly improved after treatment with low energy density picosecond laser.The results show that the alumina layer is best when the laser density is 0.5 J/cm2.Then the mechanism of the modified graphene was studied by raman spectroscopy and X-ray photoelectron spectroscopy.