Ion implantation is the standard technique used for integrated circuit fabrication in the semiconductor industry. The method involves directing a high-energy beam of ionized dopants to impinge on a substrate, resulting in a highly controlled, site-selective, and clean doping process. This level of control is crucial for all high-technology devices based on silicon electronics. It is reasonable to expect that ion implantation will play a similar role for next-generation electronics based on new materials.
In a paper appearing in Physical Review B, Ursel Bangert, Andrew Bleloch, Mhairi Gass, Ash Seepujak, and Jaap van den Berg from the Universities of Manchester, Liverpool, and Salford, all in the UK, employ ion implantation to achieve controlled impurity doping in carbon nanotubes and graphene sheets. A variety of dopants are used, such as silver, boron, nitrogen, and cobalt. Each promises to suitably tailor the surface properties of the host material. The researchers use a combination of advanced microscope techniques, including atomic resolution electron spectroscopy, to establish the fate of the implanted ions. In particular, they are able to (i) determine the location and distribution of the dopants, (ii) establish whether they are intercalated or reside within the host crystal lattice, and (iii) distinguish the influence the dopants have on the local electronic and structural environment. – Alex Klironomos