Researches On Growth Of Graphene On The Surface Of Boron-doped Diamond Films

As an important new generation of semiconductor material,diamond has excellent properties such as wide gap,high breakdown electric field,high thermal conductivity,ultra-high hardness and good chemical stability.Diamond plays an irreplaceable role in electronic power devices,UV light-emitting diodes,solid-state spin quantum devices,biological detectors and other fields.Based on the design and construction of diamond heterostructure can further broaden the application field of diamond.Graphene,as a new two-dimensional atomic layer material,has excellent electrical,mechanical,thermal and optical properties,and has important application prospects in photoelectronics,micro-nano processing,energy,biomedicine and drug delivery,which is considered as a revolutionary material in the future.Diamond and graphene are allotropes of each other,and the construction of all-carbon composite structure by growing graphene on diamond substrate may have both excellent properties of the two materials,which has important basic and applied research value.In this paper,the growth conditions of graphene were optimized by chemical vapor deposition.Graphene was grown on intrinsic diamond substrate using methane(CH₄)as carbon source.And without CH₄,graphene was prepared on the surface of boron-doped single crystal diamond(BDD)film.Raman,SEM and other techniques were used to characterize and research the growth mechanism of graphene.The main results are as follows:(1)In the vacuum tube furnace,the mixed gas of methane/hydrogen/argon(CH₄/H₂/Ar)was used as the reaction gas.The growth parameters such as gas flow ratio,temperature and growth time are optimized to generate dense graphene films on the surface of nickel(Ni)foil through the mechanism of carbon dissolution and precipitation of metal.(2)Graphene films were grown on single/poly crystal diamond films grown by microwave plasma chemical vapor deposition(MPCVD)as substrates,nickel films were prepared by magnetron sputtering as catalyst,CH₄as carbon source,in H₂/Ar mixed atmosphere at 950?.Under the action of high temperature,the surface of diamond was etched,and carbon precipitation leads to graphene accumulation on the surface.(3)Graphene films were grown on CVD boron-doped diamond substrates,and with the diamond as the only carbon source at high temperature(950?)and in the H₂/Ar mixed gas atmosphere.Experimental results show that the morphology and structural characteristics of graphene are determined by boron doping concentration,growth time and hydrogen etching on the surface.High boron doping concentration is beneficial to the growth of high-quality and low-defect few-layer graphene.In this paper,the growth of graphene under different carbon sources and substrates was studied,and its growth mechanism was discussed.The experimental results show that high quality and low defect graphene can be directly grown on the surface of boron-doped diamond,which provides a new idea for graphene synthesis,preparation and application of diamond/graphene composite structure.