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Ab initio quantum mechanical studies in electronic and structural properties of carbon nanotubes and silicon nanowires

Citation

Matsuda, Yuki (2009) Ab initio quantum mechanical studies in electronic and structural properties of carbon nanotubes and silicon nanowires. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-07222008-023323

Abstract

This dissertation focuses on ab-initio quantum mechanical calculations of nanoelectronics in three research topics: contact resistance properties of carbon nanotubes and graphenes (Chapters 1 through 3), electrical properties of carbon nanotubes (Chapter 4) and silicon nanowires (Chapter 5). Through all the chapters, the aim of the research is to provide useful guidelines for experimentalists.

Chapter 1 presents the contact resistance of metal electrode−carbon nanotube and metal electrode−graphene interfaces for various deposited metals, based on first-principles quantum mechanical density functional and matrix Green’s function methods. Chapters 2 and 3 describe inventive ways to enhance contact resistance properties as well as mechanical stabilities using “molecular anchors” (Chapter 2) or using “end-contacted” (or end-on) electrodes (Chapter 3). Chapters 1 through 3 also provide useful guidelines for nanotube assembly process which is one of the main obstacles in nanoelectronics. Chapter 4 shows accurate and detailed band structure properties of single-walled carbon nanotubes using B3LYP hybrid functional, which are critical parameters in determining the electronic properties such as small band gaps (~0.1 eV) and effective masses. Chapter 5 details both structural and electronic properties of silicon nanowires. These results lead to the findings controlling the diameter and surface coverage by adsorbates (e.g., hydrogen) of silicon nanowires can be effectively used to optimize their properties for various applications.

All the theoretical results are compared with other theoretical studies and experimental data. Notably, electronic studies using B3LYP show excellent agreement with experimental studies quantitatively, which previous quantum mechanical calculations had failed.

These studies show how quantum mechanical predictions of complex phenomena can be effectively investigated computationally in nanomaterials and nanodevices. Given the difficulty, expense, and time required for experiments, theory may now be useful for high-throughout screening to identify the best conditions and materials before performing experiments.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:band gap; effective mass; one dimensional system
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Materials Science
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Goddard, William A., III
Thesis Committee:
  • Goddard, William A., III (chair)
  • Heath, James R.
  • Bockrath, Marc William
  • Johnson, William Lewis
Defense Date:17 July 2008
Record Number:CaltechETD:etd-07222008-023323
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-07222008-023323
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:5239
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:31 Jul 2008
Last Modified:26 Dec 2012 03:16

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