Surface Decoration Of SiC Low Dimensional Nanomaterials And Their Field Emission Properties

In this thesis,aim to build SiC field emission cathode material with excellent field emission properties based on the mechanism of local field enhancement effect and lowering the work function,the surface decoration of SiC low dimensional nanomaterials were successfully synthesized via the ion sputtering and gas phase deposition process.The field emission characteristics of the obtained SiC low dimensional nanostructures before and after metal decoration been systematic evaluated.The effect and mechnism of metal nanoparticles decorated SiC field emission cathode materials on the turn-on fields,threshold electric fields and electron emission stabilities have been investigated in depth.The SiC field emission cathode materials which exhibit excellent field emission properties have been successfully preparaed.These innovative achievements have been obtained of this thesis are enumerated below.(1)The SiC nanowires were synthesized on the carbon fiber cloth substrate via the pyrolysis of polymeric precursor(PSN)process.The N2/Ar mixture was incorpored as the shielding gas during the whole pyrolysis process.These results indicated that the as-synthesized single crystal SiC nanowires follow the gas-liquid-solid(VLS)mechanism and grow along [111] direction.(2)The Au nanoparticles decorated SiC nanowires were synthesized via the ion sputtering process.The preparation of Au nanoparticles decorated SiC nanowires with different amount of Au by precise control the sputtering time.The survey results indicated that the field emission properties of SiC nanowires with Au nanoparticles decorated were variations with sputtering time.When the deposited time was setted at 15 s,compared to bare SiC nanowires,the turn-on field and threshold field decreased from 2.1 to 1.14 V/μm and 2.75 to 1.75 V/μm,respectively.While the field enhancement factor increased from 1150 to 6624.The enhanced FE behaviors were mainly attributed to the the local field enhancement effect,increased β and decreased Φ of the SiC nanowires induced by Au decoration.(3)The metal magnesium nanoparticles decorated SiC nanowires were synthesized via the vapor deposition process.Field emission properties measurements disclosed that the as-synthesized SiC nanowires with excellent electron emission stability under the 1500 μA/cm2 mianly due to the increased field emission sites density as well as the electrostatic screening effect.