טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentZeevi Gilad
SubjectMolecule Nano-Crystals Assisted Optical Visualization of
Carbon Nanotubes
DepartmentDepartment of Electrical Engineering
Supervisors Dr. Yuval Yaish
Professor Nir Tessler
Full Thesis textFull thesis text - English Version


Abstract

Carbon nanotube is a cylindrical nanostructure which has remarkable physical and chemical properties. Its miniature size (few nanometers in diameter) requires special imaging techniques for its visualization. (Standard optical microscopy is not enough).

This work describes the development and examination of a new, simple, rapid and non-invasive optical visualization technique for imaging of carbon nanotubes (CNTs). The fundamentals of the new technique include decoration of CNTs with Nano Crystals (NCs) composed of aromatic molecules. We rely on the fact that the CNT represents both a physical defect on the otherwise flat and uniform surface and chemically a more favorable nucleation site for our chosen molecules. For the visualization of the decorated CNTs we used dark field (DF) optical microscopy. Since the new method includes CNT visualization assisted by nano-crystals of organic molecules, we have named the method MAV - Molecule nano-crystals Assisted Visualization.

In this work we show the ability to decorate and image all of the CNTs growing on the substrate. We proved MAV to be completely reversible, in the sense of complete recovery of physical properties of the CNTs post visualizing. For that reason CNT field effect transistors (CNTFETs) were fabricated, both with suspended CNTs and on-surface CNTs. Comprehensive tests were performed, including:

-           Electrical characterization of the transistors before during and after MAV process.

-           Atomic Force Microscope (AFM) and Tunneling Electron Microscopy (TEM) scanning for direct measuring of complete molecule desorption from the face of the CNT.

-          Raman scans were performed to prove the complete recovery of the CNTs and the removal of all molecules residue.

When we were sure MAV does not damage the CNTs, devices were manufactured using the MAV technique, resulting in good quality devices and in a large increase in the yield.

Furthermore, we show some of MAV diversity when we present decoration of CNTs with nano-crystals of different molecules, use MAV for imaging 2D van der walls materials , using MAV to evaluate prefabricated devices and using MAV for suspended CNTs decoration.

Lastly, we present preliminary results of the sublimation process under ambient conditions of the chosen molecules, suggesting a future use of the nano-crystals for local thermometry and the molecule adsorption sensitivity to static electric charge which may detect local charge distributions. Both of these subjects deserve further research.