Carbon nanotubes synthesized by biased thermal chemical vapor deposition as an electron source in an x-ray tube

Carbon nanotubes (CNTs) with supreme field emission properties were synthesized by depositing Co-containing amorphous carbon (a-C:Co) composite films using filtered cathodic vacuum arc technique with a 15 at % Co-containing graphite target and subsequently growing CNTs using biased thermal chemical vapor deposition at 580 °C with the a-C:Co composite film as a catalyst layer. The as-grown CNTs with a thin diameter of about 10 nm have a low threshold field of 1.6 Vμm and a stable current density of 2.1 mA cm2 at 3 Vμm. Thus an x-ray source was built in a diode configuration using the CNTs as its cold electron source showing good potential in x-ray radiography.