Investigation of carbon nanotube field emitter geometry for increased current density

In this work we present field emission characteristics of four geometrically distinct carbon nanotube pillar arrays. Each cathode has a unique geometric configuration with different structural parameters such as number of edges and vertices. We present experimental data demonstrating a carbon nanotube cold field emitter with an emitted current density of 31.8 mA/cm2 at an applied field of 11 V/μm. The performance of these cathodes can be directly attributed to the electric field being enhanced along the edges and vertices of the structures. We investigated this phenomenon experimentally by changing the geometry of the carbon nanotube pillar structure. We show that by increasing the number of edges and vertices of a structure to keep the electric field screening to a minimum, the emission current can be increased.