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sidefunk wrote:
Like this evironmental shot. Good stuff. What applications are the nano tubes here being used for.
Thank you!
This question is tough I will just post the abstract of the study here:
Abstract
In this thesis properties of individual carbon nanotubes (CNTs) are studied performing measurements in electronic transport, including noise, optical spectroscopy and electron diffraction. Furthermore, novel sample geometry of suspended CNT devices is developed and a CNT synthesis setup relying on chemical vapor deposition (CVD) has been established.
Combined Raman and transport measurements on individual singlewalled nanotubes (SWNTs) are performed. These methods serve as powerful tools to determine the properties of a single device. In addition, it is possible to evaluate the reliability of these two mutually independent methods.
Suspended nanotube structures with a fully transparent path are very useful in various measurements including optical spectroscopy with reduced background noise and various transport effect neglecting the substrate effects to the CNT channel. The main benefit of the fully transparent path is that it is possible to determine the exact chiral indices of the studied tube by using the electron diffraction technique with transmission electron microscope (TEM). Such structures require new microfabrication techniques and a reliable method to prepare suspended CNTs samples is developed. In this work though, fully working electrical contacts could not be included in the measured samples due to various fabrication problems. The past and the state-of-the-art of the relevant fabrication issues are discussed in this thesis.
The suspended CNTs were studied by in-house and other collaborators using nonlinear optical techniques. The first four-wave-mixing (FWM) signal from individual semiconducting SWNT was shown. Furthermore, FWM imaging is presented which serves as a fast and sensitive imaging technique. The first observation of second harmonic generation (SHG) from an individual CNT is also presented which could be exploited for fast determination of handedness of a CNT in the future.
The last study presents the results of noise measurement on intermediate sized multiwalled carbon nanotubes (MWNTs). Such tubes can possess ballistic conduction but don't form noticeable Schottky barriers at the CNT-metal contact, as opposite compared to SWNTs. We have shown that the noise properties of such a system is described better using ballistic noise models compared to more conventional models developed for diffusive transport. Furthermore, the noise magnitude was found to be one to two orders of magnitude smaller than in similar SWNT devices.
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