Study On The Properties Of Silicon Carbide Nanowires Prepared By Metal-catalyzed Method

Silicon carbide(SiC)is attractive because of the semiconductor's wide band gap,thermal conductivity,high mechanical strength,high electrical breakdown strength,high chemical stability,oxidation and radiation resistance.Based on the significant properties of SiC,SiC nanowires also have unique elec trical,field emission,hydropholic and mechanical properties due to the 1D structure.Although the researchers already succeeded in the preparation and characterization of SiC nanowires,it remains difficult to fabricate SiC nanowaires that limits the wide application of SiC nanowires.Much controversy on its fundamental properties exists and systematic study on its optical and electrical properties as well as formation machanism are seriously lack.To solve the aforementioned problems in SiC nanowires,high quality SiC nanowires were synthesized at 900 oC by a-C and nickle deposited by magnetron sputtering in this study.(1)The effects of stacked order of a-C and nickle,synthetic temperature,holding time,and cooling rate on nanowires structural,electrical,and optical properties were systematically studied.(2)Subsequently,the superhydropolic SiCNWs/CNTs are prepared via doping Al in the formation process.(3)Finally,the oriented SiC nanowires are fabricated by using Ni-In as catalyst.It is observed that all of SiC nanowires are phase-pure with features assignable to cubic SiC.The preferred grown orientations of SiC nanowires are along the [111],and there are abundant stacking faults.The quality and yield of SiC nanowires are dependent on the growth parameters:(1)The variation of stacking order of a-C and nickle changes the morphology of SiC nanowires.(2)Increasing synthetic temperature not only increases the yield of SiC nanowires,but also improves the quality of nanowires.(3)The formation of SiC nanowires is determined by the amount of a-C and nickle.Only when the amount of a-C and nickle is appropriate,SiC nanowires could be fabricated.(4)The increase of the cooling rate not only improves the purity of SiC nanowires,but also decreases the diameter of nanowires.The ultrathin SiC nanowires could be produced by the two-step method.The effect of stacking faults on photoluminescence is studied systematically.The stacking faults changed the stacking sequence of Si-C atoms layers and formed nano segments of 4H-SiC and 6H-SiC in the 3C-SiC matrix.The mixture of polytypes leads to the shift of peaks and the addition of peaks in either Raman spectrum or Photoluminescence(PL)spectrum.The PL spectrum shows that the nanowires have three emission peaks at 357 nm,420 nm,and 535 nm,which corresponds to the emissions of the 4H-SiC,6H-SiC and amorphous Si O2,3C-SiC,respectively.The ultraviolet light emissions of SiC nanowires indicate that the nanowires have the application as a potential material for the nanooptoelectronic and light devices.The composite film of carbon nanotubes and silicon carbide nanowires was synthesized directly on the silicon substrate by doping Al.The appropriate amount of aluminum powders is a crucial factor to achieve the composite film.The composite film exhibited excellent intrinsic superhydrophobicity without any further functionalization.By using the nano/micropillar composite structure model,the presence of silicon carbide nanowires is found to be the key factor that results in the superhydrophobicity of the films.In addition,the composite films of carbon nanotubes and silicon carbide nanowires also have self-cleaning property and chemical stability.The oriented SiC nanowires are fabricated by adding In.Low-density and preferred direction SiC nanowires are formed directly on a silicon substrate using Ni-In as a catalyst.The relationship of photoluminescence and the preferred growth orientations of nanowire is studied.The photoluminescence of the oriented SiC nanowires could be improved compared with SiC nanowires without obvious preferred growth orientations.Field effect transistors were fabricated to investigate the SiC nanowire electrical behavior possessing n-channel characterization.The carrier mobility of the devices was 12.9 cm2/V·s when the Vds is 0.5 V.High quality 3C-SiC nanowires are synthesized by thermal treatment from Ni/a-C/Si sandwich films at relatively low synthetic temperature,900 oC.The self-functionalized superhydrophobic SiCNWs/CNTs and the oriented SiC nanowires could be obtained by doping.Therefore,the metal-catalyzed method is appropriate for the production of SiC nanowires with controllable performance and high quality.