Preparation And Characterization Of BN/Graphene Composite Thin Films

Graphene has extremely high carrier mobility,good thermal conductivity and high mechanical strength,these excellent properties make graphene own great potential application in the field of electronic devices and valuable research significance.Graphene grown on hexagonal boron nitride thin film substrate has much higher carrier mobility than grown on silicon substrate.And the thermal stability and deep ultraviolet absorption properties of boron nitride films make the boron nitride/graphene composite film not only can be applicated in high-frequency electronic devices,but also have a broad application prospect in UV detector pieces.Composite film material as quasi two-dimensional material,its surface morphology,molecular structure,and chemical composition and so on have a great influence on its performence.Therefore,the purpose of this paper is to establish correlations between different RF magnetron sputtering parameters,different annealing parameters with surface morphology,chemical compositions,molecular structures and so on.Then graphene was deposited on boron nitride film substrate through low pressure chemical vapor deposition method,and formed boron nitride/graphene composite films.We investigated the growth quality and growth mechanism of graphene under different deposited parameters.In addition,particular attentions have been given to study the difference between boron nitride/graphene and graphene on traditional nickel substrate.The results show that boron nitride thin films(sputtering pressure is 0.5 Pa,sputtering time is 30 min,sputtering power is 100 W)had the smooth surface undulation reached atomic level,the lowest roughness and the best absorption to ultraviolet light.With the addition of sputtering power,roughness of films surface gradually increased and the light transmittance of thin films reduced.The molecular structure of the film transform from hexagonal phase to cubic phase as the sputtering power increasing.The substrate temperature and sputtering power had a great influence on the UV absorption limit of boron nitride thin films.Graphene was acquired under sputtering power of 100 W,sputtering time of 30 min,growth temperature of 1000 ?,deposited time of 120 min with the lowest defect content and the best quality.the defect and layer number of graphene was less,and the quality of graphene was the best.The Deposition temperature and cooling rate had a crucial influence on graphene growth.When cooling rate was fast,graphene can not grow successfully.On the contrary,when cooling rate slowed down,graphene existed on boron nitride surface.The growth mechanism of graphene may be due to carbon atom formed carbide and carbon atoms precipitated when cooling.The appearance of B-C bond and N-C bond in the boron nitride/graphene film proved that B and N atoms were doped in the films and doping had great influence to electrical property.