采用磁控共溅射法在Si片表面镀NiTi膜作为碳纳米管生长的催化剂,制备出表面形貌特殊的碳纳米管薄膜,如"丘状"和"星状"的表面微结构.通过扫描电子显微镜对碳纳米管薄膜的形貌进行表征,采用二极管形式测试了碳纳米管薄膜的场发射性能.实验结果表明,这两种碳纳米管薄膜都具有优异的场发射性能,10μA/cm时的开启电场分别仅为1.02 V/btm和1.15 V/μm,在外加电场为2.4 V/μm时的电流密度分别达到4.32 mA/cm2和6.88 mA/cm2.通过场发射FN的曲线计算得到的场发射增强因子分别为10 113和6 840.这两种碳纳米管薄膜优异的场发射性能与其表面的微结构有关.表面的粗糙结构增强了部分碳纳米管的局域电场,易于发射电子.
Carbon nanotube(CNT)films with special surface morphology,such as hills-like and stars-like,were synthesized on silicon substrate,and the field emission properties were examined.The nanotubes were fabricated by thermal chemical vapor deposition using co-sputtered NiTi alloy film as catalyst.The hills-like and stars-like CNT films showed good field emission properties of low turn-on electric field and large current density.The turn-on electric field values required to obtain a 10 μA/cm2 current density for hills-like and stars-like CNT films were determined at about 1.02 V/μm and 1.15 V//μm,respectively.At an applied macroscopic field of 2.4 V//μm,the current densities reached to 4.32 mA/cm2 and 6.88 mA/cm2,respectively.The field enhancement factor β of hills-like and stars-like CNT films,calculated from the Fowler-Nordheim plots,were about 10 113 and 6 840.The good field-emission behavior iS ascribed to the combined effects of the intrinsic field emission of CNT and the rough morphology of the film surface.
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