Field-emission properties of carbon nanotubes grown using Cu-Cr catalysts

In addition to Ni, Co, and Fe, the authors show that a copper (Cu) chromium (Cr) alloy can be a good catalyst for controlled growth of carbon nanotubes (CNTs). A thermal chemical vapor deposition was used at 600 °C to deposit the CNTs, and a dual-target magnetron sputtering system was used to control the ratio of the CuCr alloy. The material properties of the CNTs, such as concentration, diameter, and density, are directly affected by the ratio of CuCr alloy, which subsequently affect the field-emission properties. Their results showed that Cr can be used to effectively control the catalytic effects of the Cu catalysts, where the quality of the CNTs could vary while the density could be controlled from 4× 107 to 5× 1010 tubes cm2. The field-emission current density of the CNT film increases with CuCr ratio from 16.4 to 4.61 and decreases when the CuCr ratio is more than 4.81 in the alloy film. When the CuCr ratio is at 4.61, the average current density peaks at 5129 μA cm2 at the applied field of 3.53 Vμm, showing an optimized field-emission property.