Single-walled carbon nanotubes (SWNTs) are often predicted to be the building blocks of future nanoelectronic devices, but development in this field is hampered by the presence of both metallic and semiconducting tubes in as-prepared samples. Although selective synthesis or separation methods offer some hope of making SWNTs with uniform electronic properties, a promising alternative involves chemical modification that specifically targets metallic SWNTs and reduces their conductivity.

Now, Jeong-O Lee from the Korea Research Institute of Chemical Technology, in Daejon, Korea and co-workers1 from Chonbuk National University and Chungbuk National University have investigated how the electronic characteristics of SWNT field-effect transistors (FETs) can be altered by chemical reactions. SWNT-FETs were immersed in a solution containing a reactive electron-deficient compound, and, after rinsing, the electrical properties of the FETs were measured and the topographic characteristics of the SWNTs investigated with atomic force microscopy. Samples were then annealed at 300 °C to remove the chemical groups and recover devices with bare SWNTs.

Of the four reactive compounds studied, all of them were shown to interact selectively with metallic SWNTs and reduce their conductivity. However, in only one case — that in which there is only a weak interaction between the electron-deficient compound and nanotube — could the original conductivity be recovered after annealing. For the other three compounds, the nanotube FETs were irreversibly modified and, in one case, some SWNTs were destroyed by the chemical reaction.