BORON DOPING OF SINGLE WALLED CARBON NANOTUBES

Open Access
Author:
Liu, Xiaoming
Graduate Program:
Physics
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
September 04, 2009
Committee Members:
  • Peter C Eklund, Dissertation Advisor
  • Nitin Samarth, Committee Chair
  • Jorge Osvaldo Sofo, Committee Member
  • Vincent Henry Crespi, Committee Member
  • John V Badding, Committee Member
  • Jayanth R Banavar, Committee Member
Keywords:
  • Carbon nanotube
  • boron doping
  • conducting films
Abstract:
This thesis addresses the improvement of electrical properties of single walled carbon nanotubes (SWNTs), grown by different techniques, by a stable substitutional boron doping. The B-SWNTs material was created in four different ways, and <1 at.% boron was found in the SWNTs bundles with electron energy loss spectroscopy (EELS). The p-type doping is confirmed by Raman spectroscopy. The Raman D-band results and the line shape of EELS spectra show that boron is fitted into the sp2 lattice of the tube wall. B-doping was found to downshift the positions of the optical absorption bands associated with van Hove singularities (E11s E22s and E11m ) by ~40 meV relative to their positions in the acid treated and annealed SWNTs. Optical transmission studies show that B-doping increases the number of free carriers, and that it does not significantly affect the optical transmittance of the B-SWNTs films in the visible region. We found that boron-doping lowers the sheet resistance by 75% of the pristine SWNTs films. Besides, boron-doped SWNTs may provide a better modification of the semi-conducting SWNTs in a stable way. We suggest that B-SWNTs films may be a potential material for future electronic devices, such as touch-screens, organic electronics device, organic solar cells and flexible display screens, because of its strengths, including transparency, high T/R&#61571; and flexibility, low cost, and easy deposition on plastic substrates.