SINGLE-WALLED CARBON NANOTUBES

Single-walled carbon nanotube (SWNT) is a rolled-up graphene. SWNT is one of the most important materials in nano-technology and many SWNT applications have been proposed. Especially, the field-effect-transistors (FETs) with SWNT-channels attract much attention. For the fabrication of such SWNT electric devices, align-ment and position control of SWNTs is important. Additionally, pure semiconducting SWNT arrays is needed for SWNT-FETs with high performance. Here, we present the growth of horizontally aligned SWNTs (HA-SWNTs) and fabricate pure-semiconducting SWNT-FETs using a selective removal technique. We used iron nanoparticles as the catalyst, ethanol vapor as the carbon source for SWNT growth. HA-SWNTs are syn-thesized on single-crystal (R-cut) quartz substrates. In advance, the R-cut quartz substrates were annealed at 900 ◦C in air for 12 h and iron was deposited in a strip pattern. The sample was heated up in Ar/H2 (3%) mixture gas. At 800 ◦C, ethanol vapor was introduced together with Ar/H2 (3%) gas and CVD growth was performed. The SWNTs were aligned along the direction of the x-axis of R-cut quartz. The density of HA-SWNTs depended on CVD conditions and the partial pressure of ethanol vapor was key point. HA-SWNTs were analyzed by scanning electron microscopy (SEM) and scanning Raman scattering spectroscopy. For selective removal of metallic SWNTs, we used thermal-lithography technique and an organic film-assiste