An Integrated Logic Circuit Assembled on a Single Carbon Nanotube

Abstract

Single-walled carbon nanotubes (SWCNTs) have been shown to exhibit excellent electrical properties, such as ballistic transport over several hundred nanometers at room temperature. Field-effect transistors (FETs) made from individual tubes show dc performance specifications rivaling those of state-of-the-art silicon devices. An important next step is the fabrication of integrated circuits on SWCNTs to study the high-frequency ac capabilities of SWCNTs. We built a five-stage ring oscillator that comprises, in total, 12 FETs side by side along the length of an individual carbon nanotube. A complementary metal-oxide semiconductor-type architecture was achieved by adjusting the gate work functions of the individual p-type and n-type FETs used.

Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy

“…We show that purified single-chirality nanotube seeds of both semiconducting and metallic SWCNTs are significantly elongated through a catalystfree VPE process, producing horizontally aligned SWCNT arrays on quartz substrates and randomly oriented SWCNTs on Si/SiO 2 substrates, with lengths more than tens of micrometres. Raman characterization confirms that the original chiralities of the nanotube seeds are preserved in the extended portion of the nanotubes, and the semiconducting nature of the grown (7,6) and (6,5) SWCNTs are further confirmed using electrical measurements on individual nanotubes.…”

“…We used atomic force microscopy (AFM) and scanning electron microscopy (SEM) to characterize SWCNTs before and after VPE cloning. Representative AFM images of (7,6) SWCNT before and after cloning using ethanol on quartz substrates are presented in Fig. 2a,b, respectively.…”

“…The measured diameter of the cloned nanotubes were approximately 0.9 nm, consistent with the (7, 6) nanotube diameter (d ¼ 0.89 nm). As control experiments, blank quartz substrates and quartz substrates deposited with DNA solution but without any nanotube seeds (6,5) Chirality-pure seeds from DNA-based separation Nanotube cloning with controlled chirality Air annealing and water vapour annealing Vapour-phase epitaxy Deposition of the seeds (7,6) Metallic SWCNT Semiconducting SWCNT (7,7) Figure 1 | Schematic illustration of the VPE process for chiralitycontrolled SWCNT synthesis. The chirality-pure nanotube seeds obtained from DNA-based separation are first deposited onto various kinds of substrates, including quartz and Si/SiO 2 , followed by air annealing and water vapour annealing processes to activate the ends for the ensuing VPE growth.…”

“…S ingle-wall carbon nanotubes (SWCNTs) possess superior electrical and optical properties, and hold great promise for electronic and biomedical applications [1][2][3][4][5][6][7][8][9][10] . As the electronic property of an SWCNT strongly depends on its chirality, the lack of synthetic control in chirality has long been recognized as a fundamental impediment in the science and application of SWCNTs.…”

“…In particular, DNA-based chromatographic separation allows purification of both semiconducting and metallic single-chirality SWCNTs through the use of different DNA sequences 12,26 . In this work, three exemplary chirality-pure (7,6), (6,5) and (7,7) SWCNT seeds with purity up to 90% are used. These serve as the starting templates for the ensuing catalyst-free, chiralitycontrolled nanotube cloning process.…”