Detection of ions and radicals by using single-walled carbon nanotubes

Single-walled carbon-nanotube (SWNT) sensors, fabricated by using alternative current dielectrophoresis, were used to detect decomposed ions and radicals in plasma. In this work, we monitored the electrical conductance of the SWNT sensors in argon (Ar) and sulfur hexafluoride (SF₆) plasma. Ar and SF₆ were decomposed in plasma status. The electrical conductance of the SWNT arrays in Ar plasma increased due to an electronic interaction between SWNT and oxidative decomposed ions. In contrast, the nanotube arrays in SF₆ plasma exhibited a drastic decrease in conductance due to the fluorination of the SWNT by decomposed radicals, rather than charge transfer by decomposed ions. These results demonstrate that electronic detection of the decomposed ions and radicals is possible with SWNT sensors.