Novel geometry of carbon nanotube field emitter to achieve high current densities for terahertz sources

We introduce a novel geometry carbon nanotube field emitter array capable of achieving high current densities. Arrays of patterned vertically aligned CNT bundles, with an open center similar to the structure of a donut, was grown directly on bulk metallic substrates. This new carbon nanotube structure, with larger edge area for enhanced edge effect, reached current densities as high as 60 mA/cm
²
at an applied DC field of less than 8 V/mum.