Application of Single-Walled Carbon Nanotube to the Probe of Scanning Tunneling Microscopy

Abstract

A single-walled carbon nanotube (SWNT) with well-defined structure has a potential as a probe of scanning microscopy. However, SWNT tip has not been applied to practical use yet because of the difficulty in the tip preparation. We have developed a technology for fabrication of SWNT tips with the yield rate of 25%. Various lengths and shapes of SWNT tips were examined as the probe of ultrahigh vacuum scanning tunneling microscopy (STM). We found that the length of SWNT was a crucial factor for the application to STM. Atomic-scale resolution could be obtained on the surface of highly oriented pyrolytic graphite with an SWNT tip shorter than 300 nm. In the case of ring type SWNT tip, which used the side wall of SWNT, the STM images depended on the scan direction due to the half-ring shape, and atomic-scale resolution could be obtained when scanned along the circumference direction of the ring. Although the stability of the SWNT tip during scanning needs to be improved, present results prove the potential of SWNT for STM probes.

Field emission from diameter‐defined single‐walled carbon nanotubes

“…[11] We found that the length of SWNT was a crucial factor for the application to STM. [11] For FE, the length of SWNT is important too. In the case of an SWNT tip with length of 1000 nm, the FE current was not stable.…”

“…On the W tip, SWNT was directly synthesized by vacuum deposition of catalyst metals and chemical vapor deposition of carbon. [11] Fabricated SWNT tips were observed by SEM, FEM, and TEM with minimized influence to the sample. The sample setup is different in each observation as shown in Fig.…”

“…In this study, we produced many W tips (length of 10 mm and 0.3 mm in diameter) simultaneously with an automated electropolishing device that had paralleled circuits of nanosecond-order switching. On the W tip, SWNT was directly synthesized by vacuum deposition of catalyst metals and chemical vapor deposition of carbon [11]. Fabricated SWNT tips were observed by SEM, FEM and TEM with minimized influence to the sample.…”

“…We have developed technologies for fabrication of SWNT tips and could produce many SWNT tips stably at the yield rate of 25%. In the previous work, SWNT tips was examined as the probe of ultrahigh vacuum scanning tunneling microscopy (STM) [11]. We found that the length of SWNT was a crucial factor for the application to STM [11].…”

“…In the previous work, SWNT tips was examined as the probe of ultrahigh vacuum scanning tunneling microscopy (STM) [11]. We found that the length of SWNT was a crucial factor for the application to STM [11]. For FE, the length of SWNT is important too.…”