Thermal Cvd Preparation Of Aligned Cnt Films And Its Field Emission Characteristics Of Study

Carbon nanotubes(CNTs) have attracted great attention in material science and technology for their semi-one-dimension structure, good electrical conductivity, excellent chemical and mechanical properties. Especially for their high aspect ratio and emitting electron at low voltage, CNTs have been considered as one of the most promising material for field electron source.Using different ways to introduce catalyst, both vertically aligned carbon nanotubes layers and randomly oriented carbon nanotubes layers were grown on silicon substrates at 700℃by thermal decomposition of acetylene. The structures of different carbon nanotubes samples were investigated by scanning electron microscopy. It is found that the catalyst inducement and density greatly affect the alignment of carbon nanotubes .Ferrocene as the catalyst precursor, double-layered aligned carbon nanotubes were grown on silicon substrates using chemical vapor deposition (CVD) by decomposing acetylene twice. The SEM images showed that the intervals of the twice introduce of acetylene is an important factor for the interface combination of carbon nanotubes layers. Maybe we can use this interval to introduce something else to form a new layer between the two carbon nanotubes layers to make functional nanocomposites materials.The field emission properties of CNTs samples have been investigated. The well-aligned CNTs film has a turn-on field of 0.78V/μm with a current density of 10μA/cm~2 and at the field of 1.08V/μm a 1mA/cm~2 current density was obtained, which can satisfy the need of FED. Its linear F-N curve shows the electron emission was field emission. The double layered CNTs film has a turn-on field of 0.36~0.46V/μm and can emit a current of 1mA/cm2 at about 0.62～0.83V/μm, its F-N curves are different between low field and high field.