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

Abstract

Carbon nanotubes (CNTs) with supreme field emission properties were synthesized by depositing Co-containing amorphous carbon $(a\text{-}\mathrm{C}:\mathrm{Co})$ composite films using filtered cathodic vacuum arc technique with a $15\mathrm{at}\%$ Co-containing graphite target and subsequently growing CNTs using biased thermal chemical vapor deposition at $580°\mathrm{C}$ with the $a\text{-}\mathrm{C}:\mathrm{Co}$ composite film as a catalyst layer. The as-grown CNTs with a thin diameter of about $10\mathrm{nm}$ have a low threshold field of $1.6\mathrm{V}∕\mu \mathrm{m}$ and a stable current density of $2.1\mathrm{mA}∕{\mathrm{cm}}^2$ at $3\mathrm{V}∕\mu \mathrm{m}$ . 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.