Fabrication Of 3C-SiC/Graphene Thin Films By Laser Chemical Vapor Deposition

The high electron mobility,high thermal conductivity,high hardness,excellent refractoriness and irradiation resistance,as well as low deposition temperature make cubic silicon carbide(3C-SiC)a promising material for harsh environment.Meanwhile,graphene exhibits fascinating properties such as ultra-high carrier mobility and ultra-high mechanical strength.In this study,3C-SiC/graphene films were prepared by laser chemical vapor deposition(LCVD).Laser provided both thermal excitation and photon excitation for the growth processes,which was beneficial for the control of deposition rate,microstructure and composition of the films.Firstly,3C-SiC films were prepared by LCVD on Si substrate.The effects of the deposition process,the precursor flow rate,the deposition temperature and the deposition pressure on the microstructure and the electrochemistry properties of the3C-SiC films have been investigated.In this study,whisker-like 3C-SiC porous films have been prepared by CVD without using metal catalyst.The SiC whiskers were naturally sharp hexagonal pyramid with a height of 300 nm,a aspect ratio in the range of 5~10 and a density of 1.3×10~8/mm~2.Besides,the specific capacitance of the porous3C-SiC film in this study reaches 4.80 mF/cm~2,which is higher than the porous SiC films prepared on Si substrate ever reported.<111>-3C-SiC epitaxial films were also prepared on Si(111)substrate by LCVD.Than,epitaxial graphene with high quality was in situ grown on the<111>-3C-SiC epitaxial films by laser radiation.The deposition temperature,deposition pressure and heating rate on the excess carbon,the orientation and the surface morphology of the<111>-3C-SiC epitaxial films have been researched.<111>-3C-SiC epitaxial films with flat surface and low concentration of excess carbon were grown as the template for the epitaxial graphene.In this study,single layer epitaxial graphene was in situ grown by laser radiation.The domain size of graphene reached a value of 26.4 nm,which is higher than the size of in situ graphene ever reported.Besides,graphene/3C-SiC composite films were in situ grown by LCVD using hexamethyldisilane(HMDS)as single precursor.The influence mechanisms of deposition pressure,deposition temperature and the flow rate of dilution gas on the composition and the conductivity of the composite films have been systematically studied.The conductivity of the composite film reaches a value of 7.61×10~5 S/m,which is 80 times of the highest value ever reported.Based on the previous study,propane was added as precursor leading to the increase of the conductivity and the growth rate at the same time.The results in this thesis would provide theoretical and technical support for the synthesis of 3C-SiC and graphene prepared by LCVD.