Study On The Growth Of Graphene By High Temperature Pyrolysis Of SiC And The Introduction Of Defects On Graphene By Plasma

Graphene has excellent optical,electrical,magnetic and mechanical properties,and has a wide range of potential applications in new energy,biosensing,electronic information and other fields.Among the many graphene preparation methods,high-temperature pyrolysis can grow directly on silicon carbide（SiC）without substrate transfer and is compatible with semiconductor processes.However,different defects are introduced in the process of preparation and application of graphene,which can greatly affect the properties of graphene.In this thesis high temperature pyrolysis method was used to explore the growth process of graphene on SiC surface,and the preparation of graphene strips and continuous graphene films was realized.Moreover,different degrees of defect introduction were carried out on graphene by plasma technology,and the graphene after defect introduction was oxidized and etched,and the graphene controllable thinning scheme on the surface of insulating substrate was explored.Based on the graphene controlled etching process,defects introduction,oxidation etching and graphically thinning of hexagonal boron nitride（h-BN）were investigated.The main work of this thesis is as follows:Firstly,the pretreatment process before the growth of graphene was explored.After ultrasonic cleaning with chemical reagents,the defects and mechanical scratches on the SiC surface were removed by H₂ etching,and the SiC substrate with regular,neat and clear steps was obtained,thus ensuring the high-quality growth of subsequent graphene.Then,the graphite crucible was selected as the growth space of graphene,and the graphene growth experiment was carried out at different temperatures.The results of atomic force microscopy（AFM）and Raman spectroscopy show that the lowest threshold of growth temperature is 1750℃.In order to explore the effect of atmosphere on the growth of graphene,SiC substrate was placed in a closed space and an unclosed space for different growth times.Meanwhile,a mixture of Ar:H₂ of50:10sccm was continuously injected into the furnace chamber.SEM results showed that the graphene grew in an irregular island shape in a confined space and gradually covered the SiC substrate completely over time.In unconfined Spaces,the graphene grows in strips and expands vertically towards the strips,eventually achieving full coverage.Subsequently,different temperatures,gases and powers were used to introduce defects into graphene.OM images showed that Ar plasma and high temperature conditions（>100℃）could cause structural damage to graphene production.After adjusting experimental parameters,O₂ plasma was used to obtain evenly distributed defect points at 100℃and 15W.The graphene with defect points was oxidized and etched,and AFM showed that the effective etched area of graphene could only be produced at 400℃or above.Finally,ductility experiment is carried out:1.Defect introduction and oxidation etching treatment are carried out on h-BN using the same experimental method.In the defect introduction experiment,the surface of h-BN also has evenly distributed defect points,and after oxidation etching,the surface of h-BN has a regular triangular etching region with directional characteristics.2.The graphic thinning experiment was carried out on the graphite sheet by combining the photolithography process and plasma technology.Under the high-energy bombardment of Ar plasma,the graphite sheet exposed to the environment was thinned or completely etched,while the graphite sheet covered by the photoresist remained on the substrate surface,thus achieving the graphic scheme of the graphite sheet.This provides an experimental basis for subsequent more diverse graphics and graphical processing methods（such as defect introduction,oxidation etching,etc.）.