Fabrication of patterned domains with graphitic clusters in amorphous carbon using a combination of ion implantation and electron irradiation techniques

Fabrication of domains containing graphitic structures in amorphous carbon (a-C) films was demonstrated. Amorphous carbon thin films with 200 nm thickness were deposited on Si substrates by ion-beam sputtering. Iron atoms in a range from 4×10¹³ to 3.7×10¹⁶ cm^-2 were doped to the a-C films by an ion implantation technique through a nickel mask with a grid of square windows of 500×500 μm and a net of 50 μm in width as a template. After removing the metal mask, the partly Fe-containing a-C films were exposed to a low-energy electron shower. In the regions where Fe atoms were implanted, Fe were crystallized and preferably diffused toward the film surface leaving graphitic structures more than 10 nm in size in the interior of the amorphous carbon films. On the other hand, the masked regions, where Fe atoms were not implanted, remained amorphous. The results suggest that regions, which consist of amorphous domains and graphitic domains, can be intentionally arranged in a-C thin films.